Cruel fate has cut short the judicial career of one of the greatest family lawyers of our times. He explains why in his article, ‘Sir Nicholas Mostyn shares his experience of living with Parkinson’s’ [2023] IFL 67. In the form of a revelatory interview (see p 89 below) with Alexander Chandler KC, Sir Nicholas has given us an apologia pro vita sua. The Editor rightly thought it should be published alongside an appreciation from another perspective.

As much through choice as because of anticipated objections in august quarters, Mostyn J never sought to ascend to the higher reaches that his vast knowledge, high intellect and tremendous industry would more than have justified. Dare one be allowed to say that his wise choice has immeasurably benefitted us all. As the outstanding puisne of his era, he has achieved much more – and much more of enduring importance – than many who have risen much further.

Called in 1980, Nicholas Mostyn was immeasurably lucky to have as a pupil master the late, great, much-loved and much-lamented Peter Singer (Singer J, 1993–2010). For Nicholas it gave him a lifelong friendship, broken only when Peter died in December 2018 and marked by the remarkable address he delivered at Peter’s funeral in Southwark Cathedral in January 2019 (reprinted in At A Glance 2019–2020) and his subsequent tribute, ‘Sir Peter Singer (1944–2018)’ [2019] Fam Law 105. For us it led to a remarkably creative partnership, lasting from 1992 to 2018, which, combining Mostyn’s innovative ideas with Singer’s editorial skills and Dick Warner’s business acumen as owner of Class Publishing, was to give us Class Legal.

Whatever the state of the substantive law in the 1990s in relation to ancillary relief (financial remedies as we would now call it), practice and procedure were not in a happy condition. If that seems unduly harsh we need only to consider Booth J’s landmark judgment in Evans v Evans [1990] 1 WLR 575, [1990] 1 FLR 319, and Lord Hoffmann’s excoriating speech in Piglowska v Piglowski [1999] 1 WLR 1360, [1999] 2 FLR 763. What was to be done?

For Mostyn the first notable step was the publication in 1992 of the first edition of At A Glance: Essential Court Tables for Ancillary Relief (more recently re-branded as Essential Tables for Financial Remedies), the brainchild of Singer, Mostyn and the late and much-lamented Val le Grice, published by the Family Law Bar Association (FLBA) and produced for them by Class Publishing. It marked a decisive break with the past. Remarkably innovative in function, content, presentation and, not least, format, it was an entirely new kind of practitioner’s handbook, and even today there is nothing to match it, either in relation to its own subject-matter or, so far as I am aware, in any other field of legal practice. Its purpose was explained in a Preface which although anonymous was plainly written by Singer, for it consisted of a characteristically laboured parable on the theme of Romeo and Juliet; Mostyn’s hard work in the boiler room was exemplified by the fact that he asserted the copyright in no fewer than five of the 21 Tables as well as in the thematically arranged Table of Leading Cases which still remains, 30 years later, such a valuable feature of At A Glance.

At A Glance was of course only the first of a number of similarly innovative works to emerge from Class Legal. The first edition of Financial Remedies Practice (FRP), another Singer-Mostyn venture, in 2011, was followed by the Dictionary of Financial Remedies in 2013, the Dictionary of Private Children Law in 2021, the Financial Remedies Journal in 2022, and the Dictionary of TLATA and Inheritance Act Claims in 2023. Although neither edited nor authored by Mostyn (responsibility for all of them lies with HHJ Edward Hess), his fingerprints can be detected on the Dictionary of Financial Remedies. But perhaps his greatest work was and remains FRP; although assisted by the other distinguished lawyers whose names also adorn the title page, Mostyn was from the outset responsible for all the heavy lifting on FRP which remains distinctively a monument to his erudition and mastery of the sources. Its up-to-date coverage of both the family and the civil case-law is so extensive – seemingly exhaustive – as to put the poor old White Book to shame.

Another less immediately obvious feature of At A Glance and its successors was the extensive use by both Singer and especially Mostyn of IT in its preparation. They had very early on seen that the future was electronic. Indeed, as Rhys Taylor tells us, in his invaluable blog, ‘The Class Legal Financial Remedies Skyline: a Review’, published online on the Financial Remedies Journal website in May 2022, FRP was ‘Designed originally (so Sir Peter Singer once told me) to be electronic only’.

If At A Glance was Mostyn’s first notable step in this context, the second was even more important – his membership, in the company of a galaxy of legal talent, of the Ancillary Relief Working Party (ARWP), set up by the then Senior District Judge, Gerald Angel, in 1992 and subsequently chaired by Sir Mathew Thorpe, which led to the 1996 ancillary relief pilot scheme. For those who take the product of their labours for granted – and the numbers who can now recall the bad old days is, in the nature of things, much reduced – it takes an effort of imagination to appreciate just how important and pregnant with future change the work of the ARWP was. We are much indebted to Mostyn for collating the various recollections of those far-seeing pioneers on the ARWP, his own included, in The Pilot Scheme Jubilee – The story behind the 1996 ancillary relief pilot scheme, published by Class Legal in 2021. One of the skills he was able to bring to the ARWP was, he tells us, ‘some computing know-how (learned at Ampleforth in the 1970s)’ – so we have much to thank the Benedictines for – but perhaps his greatest contribution was as draftsman of the proposed new rules and creator of the new Form E:

‘I recall many hours in front of my then cutting-edge IBM PS/2 computer (storage 720 KB) grappling with the table function in my word processing program, WordPerfect … I eventually came up with a template – Form E.’

Class Legal, it hardly needs saying, has long been and remains a leader in the provision of interactive IT systems for financial remedies practitioners, a field of endeavour which Mostyn has very much made his own, although in saying this I must not minimise the enormous impact of his original and long-time collaborator, Peter Singer, or overlook the invaluable contributions of his co-authors, particularly in more recent years.

It was as long ago as 1991 that Mostyn demonstrated to an initially sceptical FLBA audience at Cumberland Lodge an electronic interactive family assets spreadsheet, able to perform in a couple of minutes what would have taken hours to complete using pen, paper and calculator. Of his audience, which included the then President and other senior figures, it may be said that they gasped and stretched their eyes. Thirty-two years later, at Cumberland Lodge in May 2023 Mostyn reprised his earlier demonstration. The fact that to his modern audience there seemed nothing at all remarkable, shows what a very long way we have come from those electronically innocent days of 1991 and reminds us of just how important Mostyn’s pioneering and innovative work in this field has been in creating our modern world.

In 1993 came Child’s Pay: The Complete Guide to the Child Support Act 1991 and the Subordinate Legislation, published by Class Publishing, on the new Child Support Scheme. It was accompanied by an electronic calculating tool, provided on a floppy disc, giving the user a quick way to calculate accurate child support figures. When the third, and final, edition was published in 2002 this invaluable tool was provided on a CD.

For once, the publisher’s blurb on the back cover spoke no more than the truth, describing Mostyn as ‘a renowned and experienced computer program deviser’ and identifying him in this context as the author not merely of Child’s Pay but also of Capitalise, Quantum Hop (later Skip) and @eGlance. Capitalise was and remains the pre-eminent electronic Duxbury calculator, an unrivalled tool for capitalising income needs personalised to the individual circumstances of the case. Quantum Skip (now Quantum Cloud) was in origin an electronic tool for preparing a Form E program. It now gives users all the tools they need to complete their family law forms, court orders, chronology, schedule of assets and more in a fully digital cloud-based system. @eGlance (now At A Glance Cloud), the online version of At A Glance, is a cloud-based toolkit and knowledge library enabling financial remedy practitioners to carry out a whole range of useful calculations, print out formatted reports, browse leading cases, stay up-to-date with developments in the Financial Remedies Court (FRC), and access extensive and up-to-date commentary on the Family Procedure Rules 2010. More recently they have been joined by Family Orders Online, designed to streamline the drafting of standard family court orders: it contains the latest library of standard family orders, always kept up-to-date, and enables the user to merge core case information into the order, including such details as the applicant and respondent, children and court.

These electronic systems, with their array of tools, calculators and report-printing, form-printing and order-printing features, give the practitioner everything they need. The success of Mostyn and Class Legal in providing cutting-edge electronic systems of the kind that practitioners need stands in painful contrast with the still stuttering attempts of the powers that be, more than 6 years after the ill-fated Court Modernisation Programme started in 2016, to provide remotely comparable systems for court users. Why have Mostyn and Class Legal been so successful? It is surely because they have always had the deep understanding of the family justice system and how it operates, and of the needs of the professionals and others who use it, which unhappily is and always has been so markedly and deplorably lacking in the Ministry of Justice and HM Courts & Tribunals Service (HMCTS) and their predecessors. And from the word go Class Legal has had a really good helpline where the phone is answered immediately by someone speaking comprehensible English and the problem is solved.

In addition to his computing skills, Mostyn considers himself, with every justification so far as the non-expert can judge, to be a good mathematician and statistician, with a particular interest in the laws of probability – a subject I must return to below.

The underlying theme which infuses all this output was Mostyn’s early appreciation that, as he very recently put it (R (MNL) v Westminster Magistrates’ Court [2023] EWHC 587 (Admin) at [49]), ‘Procedural rules exist for a purpose, and that purpose is to ensure that every legal cause is despatched not merely efficiently, but fairly.’ It is a theme which, as we shall see, has remained a constant throughout his subsequent judicial career, generating many important judgments. An early example, expressed in characteristically trenchant terms, happily consequential in its effect of stamping out widespread abuse, and still (see Peel J in J v H [2022] EWFC 133 at [3]) the ‘locus classicus’, was L v K (Freezing Orders: Principles and Safeguards) [2013] EWHC 1735 (Fam), [2014] Fam 35.

If I emphasise his focus on practice and procedure, it is important also to acknowledge Mostyn the historian of family law. He has never been concerned just with the here and now and has a deep scholarly knowledge and awareness of the importance of the history of family law, nurtured when at Bristol University he wrote an undergraduate dissertation entitled Canonical annulment of marriage compared with English law, with special reference to capacity, consent and consummation. His 1999 lecture to The Family Law Conference in Queensland, published as ‘“Justice Must be Seen to be Done” – Open Justice and Family Law’ [1999] IFL 80, is a penetrating historical analysis of an enduringly important topic which remains as compelling today a quarter of a century after it was written. He opened with a quotation from Lawrence Stone’s Road to Divorce: England 1530–1987, 1990, the first of Stone’s great trilogy of magisterial works on the history of marriage and divorce, followed by two volumes of case-studies, Uncertain Unions: Marriage in England 1660–1753, 1992, and Broken Lives: Separation and Divorce in England 1660–1857, 1993. Two decades later in Hasan v Ul-Hasan, decd and Another [2021] EWHC 1791 (Fam), [2022] Fam 1, [2022] 1 FLR 1033 at [31], Mostyn told us, the context being his discussion of the common law action for criminal conversation (crim con), that he had ‘re-read chapter IX of Lawrence Stone’s magisterial work Road to Divorce’. One wonders how many of his brethren are even aware of let alone as deeply read in Stone as is Mostyn. This is a topic to which I must return when considering his judgments.

But what of Mostyn the barrister? We catch a glimpse of him as a junior in the recent ‘Interview with Sir Mathew Thorpe’ [2023] 1 FRJ 68 at 70: ‘I have profound admiration for Nicholas Mostyn. We were in chambers together and when he was first in chambers he was my junior of choice if there was not a lot of money about … And he was so clever’. The account in his Apologia of the 5 years Mostyn spent as his junior of choice shows how ‘incredibly influential’ Nicholas Wilson QC was, how he ‘learned so much from him about how to cross-examine, how to prepare cases, how to deal with clients’, and how feels ‘so lucky to have spent those years working with him.’ All that no doubt stood him in very good stead, for when Mostyn took Silk in 1997 he was still only a youthful 39 – he had been born in July 1957 – then as now pretty young for a family Silk.

The same year he was one of the founding editors of the journal International Family Law: see the deservedly warm tributes from the current editors and from Rebecca Bailey-Harris in [2023] IFL 65 and 66–67.

1997 was a good time for a thrustingly ambitious ‘money’ junior to be taking Silk.

In the first place, the previous decade had seen the disappearance onto the Family Division Bench of many of the leading ‘money’ Silks: Mathew Thorpe (1988), Peter Singer (1993), Nicholas Wilson (1993) and James Holman (1995), to be followed by Hugh Bennett (1995), David Bodey (1999), Paul Coleridge (2000) and Florence Baron (2004). Increasingly that left the field clear for Mostyn to achieve the pre-eminence which marked his last decade in practice.

But there was to be another, for him a profoundly significant if in 1997 entirely unexpected, development which was to propel Mostyn ever upwards. When in July 1996 the Court of Appeal handed down its judgment in Dart v Dart [1996] 2 FLR 286 it seemed that the substantive law of ancillary relief as crafted a generation previously by Lord Denning MR and, more especially, by Ormrod LJ was settled and impervious to change: consider Thorpe LJ’s brutal put down of one Munby QC. And the House of Lords, after all, dismissed Mrs Dart’s petition for leave to appeal. But within 4 short years the world had changed. In February 1999 the House of Lords granted both Mr and Mrs White permission to appeal, and on 26 October 2000 handed down their landmark decision: White v White [2001] 1 AC 596, [2000] 2 FLR 981. This, as is well known, was to open up an immense field of highly paid work for the Bar in so-called ‘big money’ cases which to this day shows no sign of abating.

Following White v White, in which Mostyn had appeared throughout for Mr White, he appeared in a galaxy of ‘big money’ cases of both legal and, often also of more general, interest. One thinks for example of: Lambert v Lambert [2002] EWCA Civ 1685, [2003] Fam 103, [2003] 1 FLR 139; Parlour v Parlour [2004] EWCA Civ 872, [2005] Fam 171, [2004] 2 FLR 893; Sorrell v Sorrell [2005] EWHC 1717 (Fam), [2006] 1 FLR 497; Miller v Miller [2006] UKHL 24, [2006] 2 AC 618, [2006] 1 FLR 1186; McCartney v McCartney [2008] EWHC 401 (Fam), [2008] 1 FLR 1508; Spencer v Spencer [2009] EWHC 1529 (Fam), [2009] 2 FLR 1416; and Radmacher (formerly Granatino) v Granatino [2010] UKSC 42, [2011] 1 AC 534, [2010] 2 FLR 1900 – heard before nine judges of the Supreme Court it was Mostyn’s last case at the Bar.

Some journalists apparently nicknamed him ‘Mr Payout’ and it was said that at the height of his career Mostyn was being paid £500 an hour. Whatever the truth of that, I comment only that had Mostyn chosen to practise at either the Chancery or the Commercial Bar – which his formidable intellect would have made entirely possible – his earnings would have been very much higher than the figure bandied about.

I had the pleasure of appearing with Mostyn only once, when we appeared, he for Mr and I for Mrs White, both of whom were seeking permission to appeal to the House of Lords. Most unusually, and for reasons which were never explained, the Appeal Committee decided that there should be an oral hearing. Mr White’s petition for leave having been issued first, Mostyn opened the batting. I suspect he would agree that he made little headway; the Committee seemed uninterested and unimpressed, one of their Lordships remarking, as I recall, that as the case was all about discretion why should the House consider it. Following on for Mrs White, I made common cause with Mostyn for, although if permission was granted the parties would be bitterly at odds, at this stage they had the same interest in obtaining permission. (Lest it be thought that I succeeded where Mostyn had failed, I make no such claim: permission to appeal was granted only after the penny suddenly dropped with their Lordships that both parties were seeking permission.) Soon after, Mrs White dispensed with my services, as she had with both of my predecessors, so I never had the opportunity as a barrister of encountering Mostyn in full adversarial mode.

Mostyn appeared before me in Sulaiman v Juffali [2001] EWHC 556 (Fam), [2002] 1 FLR 479, in Al-Khatib v Masry [2002] 1 FLR 1053, and, most notoriously, in Spencer v Spencer [2009] EWHC 1529 (Fam), [2009] 2 FLR 1416. His advocacy was intellectually compelling and enhanced by the clarity of expression and confidence of manner which are so potent and persuasive when it comes to what Pliny (Ep I, xx, 14) in a letter to his friend Tacitus some two Millenia ago famously described as ‘working on the minds of judges’. Spencer, of course, is best known in many quarters because of some choice words which Mostyn reportedly used of me following my judgment. Given their public notoriety, I take this opportunity to make clear that I have never borne any grudge against him for what he said. How often have we all come out of court after a long and gruelling day which has not gone entirely as expected and made some unflattering comment about the judge which we would be mortified to think would ever come to the judge’s ears – his only mistake was not to think about the possible consequences if his words were ever to become public.

Mostyn became a Deputy High Court Judge in 2000 and was appointed a judge of the Family Division, in succession to Bennett J, in 2010, sitting also as a judge of the Court of Protection, in the Administrative Court (from 2014) and, of course (also from 2014) in the newly created Family Court. Over an immensely productive judicial career spanning more than two decades he has delivered many hundreds of judgments. Here I must be ruthlessly selective, focusing primarily on his judgments in relation to financial remedies – money – cases. My selection, needless to emphasise, is necessarily subjective. I must however place on record that, as he has often said, the judgment of which Mostyn is most proud is not a family case, but the one in the Administrative Court where he quashed the Personal Independence Payment restrictions: R (RF) v Secretary of State for Work and Pensions (Mind and Another Intervening) [2017] EWHC 3375 (Admin), [2018] PTSR 1147.

During his 10 years as a Deputy High Court Judge, Mostyn gave many judgments which found their way into the law reports. Probably the most important, and still the leading authority in relation to the handling of third-party claims and maintenance pending suit, is TL v ML (Ancillary Relief: Claim against Assets of Extended Family) [2005] EWHC 2860 (Fam), [2006] 1 FLR 1263. In contrast, GW v RW (Financial Provision: Departure from Equality) [2003] EWHC 611 (Fam), [2003] 2 FLR 108, a pioneering decision on the application of White v White, has had a more chequered career. His thesis that cohabitation which ‘moves seamlessly … to marriage’ should be added to the duration of the marriage – ‘the law in this area is not moribund but must move to reflect changing social values’ – has endured. In contrast, his thesis in relation to short marriages has not survived subsequent judicial scrutiny, requiring him, as he put it in E v L (Financial Remedies) [2021] EWFC 60, [2022] 1 FLR 952 at [43], ‘figuratively [to] hold my hand in the flames and recant.’ Others which deserve to be recorded are: Le Foe v Le Foe [2001] 2 FLR 970, dealing with the rights of the mortgagee where the husband had fraudulently mortgaged the matrimonial home; W v W (Ancillary Relief: Non-Disclosure) [2003] EWHC 2254 (Fam), [2004] 1 FLR 494, where the husband’s Form E presented him as being insolvent although he had assets of about £2,700,000; and Rossi v Rossi [2006] EWHC 1482 (Fam), [2007] 1 FLR 790, on the question of delay in bringing proceedings.

From Mostyn’s career as a High Court Judge from 2010 to 2023 I select the following from a very long list of highly significant money judgments: S v AG (Financial Orders: Lottery Prize) [2011] EWHC 2637 (Fam), [2012] 1 FLR 651 (whether lottery win by one spouse to be characterised as matrimonial or non-matrimonial property); N v F (Financial Orders: Pre-Acquired Wealth) [2011] EWHC 586 (Fam), [2011] 2 FLR 533; BJ v MJ (Financial Order: Overseas Trust) [2011] EWHC 2708 (Fam), [2012] 1 FLR 667 (treatment of trusts in division of assets following divorce); B v S (Financial Remedy: Marital Property Regime) [2012] EWHC 265 (Fam), [2012] 2 FLR 502; AC v DC (Financial Remedy: Effect of s.37 Avoidance Order) [2012] EWHC 2032 (Fam), [2013] 2 FLR 1483; DR v GR (Financial Remedy: Variation of Overseas Trust) [2013] EWHC 1196 (Fam), [2013] 2 FLR 1534 (principles applicable to joinder of trustees and/or underlying companies of a trust in variation of settlement cases); SA v PA (Premarital Agreement: Compensation) [2014] EWHC 392 (Fam), [2014] 2 FLR 1028; AB v CB (Financial Remedies: Variation of Trust) [2014] EWHC 2998 (Fam), [2015] 2 FLR 25; JL v SL (Appeal: Non-Matrimonial Property) [2014] EWHC 3658 (Fam), [2015] 2 FLR 1193; SS v NS (Spousal Maintenance) [2014] EWHC 4183 (Fam), [2015] 2 FLR 1124 (important guidance on principles relevant to applications for spousal maintenance); JL v SL (No 2) (Financial Remedies: Rehearing: Non-Matrimonial Property) [2015] EWHC 360 (Fam), [2015] 2 FLR 1202; Goyal v Goyal [2016] EWFC 50, [2016] 4 WLR 170, [2017] 2 FLR 236 (pension sharing order not available in relation to overseas pension); Quan v Bray [2018] EWHC 3558 (Fam), [2019] 1 FLR 1114 (spousal maintenance); Ipekçi v McConnell [2019] EWFC 19, [2019] 2 FLR 667 (pre-nup not upheld); CB v KB (Financial Remedies: Calculation of Income Streams and Child Support) [2019] EWFC 78, [2020] 1 FLR 795 (Duxbury amortisation); OG v AG (Financial Remedies: Conduct) [2020] EWFC 52, [2021] 1 FLR 1105 (litigation conduct); E v L [2021] EWFC 60, [2022] 1 FLR 952 (short childless marriage); BT v CU [2021] EWFC 87, [2022] 2 FLR 26 (COVID-19 and Thwaite/Barder); Collardeau-Fuchs v Fuchs [2022] EWFC 135 (pre-nup and child support); and James v Seymour [2023] EWHC 844 (Fam) (child support). One could go on for so long.

In his remarkable Valete for Mostyn, HHJ Edward Hess made an interesting and important point about his judgments: [2022] 2 FRJ 75. Paying tribute to what he called Mostyn’s ‘very remarkable’, indeed ‘phenomenal’ contribution to the world of financial remedies, he went on:

‘but above all he will be remembered for the authority and clarity of his judgments in the field of financial remedies. Participants in this field well know that, on a wide range of subjects (e.g. joinder, needs, Legal Services Payment Orders, child maintenance, costs, Maintenance Pending Suit, lump sum variation, setting aside, company valuation), extracts from his judgments come close to representing a statutory codification of the relevant law. This is no accident, but the product of a high intellect, prodigiously hard work and a practitioner’s instinct for knowing where guidance is needed.’

But merely to identify those of Mostyn’s judgments which are of legal importance seriously underplays their wider significance.

His judgments, as well as being always beautifully crafted, notable for their clarity and (at least by contemporary standards) conciseness, have a much wider sweep than most. He is a great wordsmith, prolific in the deployment of aphorisms and the crafting of metaphors. Consider, for example, SP v EB and KP [2014] EWHC 3964 (Fam), [2016] 1 FLR 228 at [29], where, rejecting a wholly misconceived application by counsel for ‘amplification of inadequate reasons’, he said ‘Nor do I need to incant mechanically passages from Re M [In re M and Another (Children) (Abduction: Rights of Custody) [2007] UKHL 55, [2008] AC 1288, [2008] 1 FLR 251] as if I were a pilot going through the pre-flight checklist.’ Or JL v SL (No 3) (Post-judgment Amplification) [2015] EWHC 555 (Fam), [2015] 2 FLR 1220 at [13], speaking of the use of Duxbury calculations, ‘Generally speaking in most human fields the best prophet of the future is the past.’ Or R (ZAI Corporate Finance Ltd) v AIM Disciplinary Committee of the London Stock Exchange PLC [2017] EWHC 778 (Admin) at [18] (appeal dismissed [2017] EWCA Civ 1294, [2017] Bus LR 2139):

‘the decision … may have been laconic, but that is of the nature of case management decisions. When it comes to case management decisions in my opinion the general rule should be that “less is more”.’

Or R (Sandy) v Secretary of State for the Home Department [2023] EWHC 640 (Admin) at [47]:

‘There is no doubt that in the world of judicial review proportionality has advanced like a cuckoo, occupying the common law nest of traditional assessment, laying its continental eggs in it, and ejecting its home-incubated Wednesbury hatchlings.’

Or Cummings v Fawn [2023] EWHC 830 (Fam) at [18], where he described the discretionary range for the assessment of the ‘needs’ principle as ‘a line of books on a shelf bracketed left and right by book-ends.’

Perhaps the most significant was his introduction into our jurisprudence in 2015 of the white leopard as a metaphor for the conceivable but utterly improbable: see JL v SL (No 2) (Appeal: Non-Matrimonial Property) [2015] EWHC 360 (Fam), [2015] 2 FLR 1202 at [22], [40], approved by the Privy Council in Scatliffe v Scatliffe (British Virgin Islands) [2016] UKPC 36, [2017] AC 93, [2017] 2 FLR 933 at [25]. Of the white leopard it can fairly be said that it has been frequently cited but as yet hardly ever sighted, though as Baker J, as he then was, amusingly commented in XW v XH [2017] EWFC 76, [2019] 4 WLR 83, [2019] 1 FLR 481 at [220]:

‘Mostyn J may be right to describe the concept of special contribution as “rare as a white leopard”. As demonstrated by the Court of Appeal decision in Work v Gray [[2017] EWCA Civ 270, [2018] Fam 35, [2017] 2 FLR 1297], however, it is neither a unicorn nor, for that matter, a dodo.’

Mostyn is very well read in the writings of Scalia J, which he quotes with the evident admiration properly due to a noted judicial master of language.

In Carmarthenshire County Council v Y [2017] EWFC 36 at [8], he cited Scalia’s discussion in Crawford v Washington (2004) 541 US 36, 62, of the Sixth Amendment to the US Constitution:

‘It commands, not that evidence be reliable, but that reliability be assessed in a particular manner: by testing in the crucible of cross-examination. The Clause thus reflects a judgment, not only about the desirability of reliable evidence (a point on which there could be little dissent), but about how reliability can best be determined. Cf. 3 Blackstone, Commentaries, at 373 (“This open examination of witnesses … is much more conducive to the clearing up of truth”); M. Hale, History and Analysis of the Common Law of England 258 (1713) (adversarial testing “beats and bolts out the Truth much better”).’

Mostyn returned to this in Sait v The General Medical Council [2018] EWHC 3160 (Admin) at [49]–[51], and again in AO v LA [2023] EWHC 83 (Fam) at [50], [60].

In OG v AG [2020] EWFC 52, [2021] 1 FLR 1105 at [69], where the context was the incommensurability of different kinds of commercial contribution within a family business, he cited Scalia J’s memorable statement in Bendix Autolite Corp v Midwesco Enterprises Inc (1988) 486 US 888, 897, that it is like ‘judging whether a particular line is longer than a particular rock is heavy.’

In NB v MI [2021] EWHC 224 (Fam), [2021] 2 FLR 786 at [94], he cited Scalia’s aphorism that ‘the rule of law is the law of rules.’

In R (Akinsanya) v Secretary of State for the Home Department [2021] EWHC 1535 (Admin), [2021] 1 WLR 5454 at [69], he cited Scalia’s statement that:

‘A text should not be construed strictly, and it should not be construed leniently; it should be construed reasonably, to contain all that it fairly means. But while the good textualist is not a literalist, neither is he a nihilist. Words do have a limited range of meaning, and no interpretation that goes beyond that range is permissible.’

If Scalia is his favourite, Mostyn has deployed the words of other American judges. In DL v SL [2015] EWHC 2621 (Fam), [2016] 2 FLR 552 at [6], he cited the famous aphorism of the great Brandeis that ‘sunshine is said to be one of the best disinfectants’, though, it has to be noted, allowing much less sunshine to penetrate the Family Division then than he would now believe appropriate. And in R (Sandy) v Secretary of State for the Home Department [2023] EWHC 640 (Admin) at [49], he cited Cardozo (The Growth of the Law, 1924) to telling effect on the limitations inherent in even the widest judicial discretion:

‘Complete freedom – unfettered and undirected – there never is. A thousand limitations – the product some of statute, some of precedent, some of vague tradition or of an immemorial technique – encompass and hedge us even when we think of ourselves as ranging freely and at large … Narrow at best is any freedom that is allotted to us.’

But his wide range of citations is not confined to the merely legal. In R (Delo) v Information Commissioner and Another [2022] EWHC 3046 (Admin) at [8], in the context of considering the history of the role and functions of the office of the Information Commissioner and his predecessors, he cited Lord Acton’s aphorism that ‘the value of history is certainty – against which opinion is broken up.’

And one of his favourite quotations, though so far as I am aware it has never featured in a judgment, is that of the future Marechal Foch allegedly exclaiming on a particularly dark day during the Great War, ‘Mon centre cède, ma droite recule, situation excellente, j’attaque.’

And he revels in the purely literary.

In Fresh View Swift Properties Ltd v Westminster Magistrates’ Court [2023] EWHC 605 (Admin) at [27], where the context was the law of forfeiture, Mostyn cited Gilbert and Sullivan’s famous lines in Act II of The Mikado: ‘My object all sublime / I shall achieve in time — / To let the punishment fit the crime — The punishment fit the crime.’

But the greatest example is surely his judgment in SS v NS (Spousal Maintenance) [2014] EWHC 4183 (Fam), [2015] 2 FLR 1124 at [40], where, having commented that ‘the assessment of need is elastic, fact-specific and highly discretionary,’ he cited Shakespeare’s King Lear, Act 2, Scene 4: ‘For as King Lear pointed out, needs are exceedingly hard to reason; even the poor have things superfluous to their basic needs; and most luxuries are strictly unnecessary.’ It got better, for at [55] he said:

‘[Counsel] invites me to peer into the future and to predict that for at least 7 more years … the husband will earn bonuses at approximately the same net rate as the average for the last three years … He in effect invites me to apply Lord Byron’s aphorism that “the best prophet of the future is the past”. On the other hand I recall … the epigram of the great atomic physicist Niels Bohr that “prediction is very difficult, especially about the future”. I also recall Mark Twain’s acute observation that “prophecies which promise valuable things, desirable things, good things, worthy things, never come true.”’

Sometimes the literary allusion is less obvious. Mostyn’s judgment in B v S (Financial Remedy: Marital Property Regime) [2012] EWHC 265 (Fam), [2012] 2 FLR 502 at [76] is so characteristic in so many ways of his writing that it deserves quotation in full:

‘The reason that the sharing principle is sometimes advocated as being applicable to a periodical payments claim is to reflect the theory that post-separation earnings derive from an earning capacity built up during the marriage which is, in some intangible way, a piece of matrimonial property there to be equitably or fairly shared. The high point of that theory is the dictum of Lady Hale which I have quoted above viz “the main family asset is the husband’s very substantial earning power, generated over a lengthy marriage”. As a theory it is problematic, because at the end of the day the only reason there is income after separation is because of work done after separation. A footballer who earns £100,000 per week earns that because he is on the pitch playing football. Certainly, the skills he was born with, and the development of those skills (which may well have happened during his marriage), are all reasons why he can command his salary, but he will not get paid it unless he plays football. The footballer has to fill the unforgiving minute with sixty seconds’ worth of distance run after the marriage.’

But how many of his learned readers would have appreciated that the ‘unforgiving minute’ comes from the final verse of Kipling’s If – ‘If you can fill the unforgiving minute / With sixty seconds’ worth of distance run, / Yours is the Earth and everything that’s in it’.

I have already noted Mostyn’s deployment of legal history in his judgments. In R (Wakenshaw) v Secretary of State for Justice [2018] EWHC 2089 (Admin) at [28]–[30], he observed that ‘There is nothing new about executive interference in the tenure of judges’ and proceeds to give two historical examples taken from the reigns of Charles I and Charles II.

In his paper, ‘Family Law – Not The Poor Relation’, delivered (remotely from France) to the 19th National Family Law Conference Adelaide, South Australia on 16 August 2022, he referred to ‘La re´volution de 5 Brumaire CCIX (Cinquie`me Brumaire An Deux Cent Neuf)’. Thankfully a footnote explained ‘corresponding to 26 October 2000 [being the date of the House of Lords’ judgment in White] under the new republican calendar adopted by the revolutionary National Convention in October 1793 to mark the “era of liberty”. It was abolished by Napoleon on 1 January 1806.’

Combining his interests in language and history, and illustrating his characteristic use of the interrogative footnote, is R (Sandy) v Secretary of State for the Home Department [2023] EWHC 640 (Admin) at [28]. Having noted the words ‘certificate of naturalization’ in British Nationality and Status of Aliens Act 1914, s 2(1), whereas in British Nationality Act 1948, s 10(1) the same words appeared as ‘certificate of naturalisation’, he added this footnote: ‘At some point between 1914 and 1948 the Parliamentary draftsman abandoned the Oxford spelling of the verb suffix -ize in favour of -ise.’ The footnote implicitly asks but leaves unanswered the interesting question: When? Those wishing to pursue it can, as a first port of call, consider the successive editions of Fowler’s Modern English Usage.

But for present purposes what is of greater interest are the judgments in which Mostyn deploys his learning in the history, including the history of the canon law and of the pre-1858 ecclesiastical courts, of the law relating to marriage, to divorce and to financial relief. There are many examples. I note in particular SS v NS (Spousal Maintenance) [2014] EWHC 4183 (Fam), [2015] 2 FLR 1124, NB v MI [2021] EWHC 224 (Fam), [2021] 2 FLR 786, Hasan v Ul-Hasan, decd and Another [2021] EWHC 1791 (Fam), [2022] Fam 1, [2022] 1 FLR 1033, E v L [2021] EWFC 60, [2022] 1 FLR 952 and Tousi v Gaydukova [2023] EWHC 404 (Fam), where, amongst the most considerable learning, reference is made (at [31]) to the period from the time of the Decretal of Alexander III in 1180 up to the Tametsi decree of the Council of Trent in 1563.

Most recently Mostyn has displayed his profoundly deep and impressive historical researches in the important sequence of judgments addressing – one is tempted to say denouncing – what he calls a ‘culture of secrecy’ in the FRC and which is, he asserts both unprincipled and, indeed, unlawful: starting on 1 November 2021 with BT v CU [2021] EWFC 87, [2022] 1 WLR 1349, [2022] 2 FLR 26, next A v M [2021] EWFC 89, [2022] 1 FCR 445, and Xanthopoulos v Rakshina [2022] EWFC 30, [2022] 2 FCR 712, culminating on 13 June 2022 with Gallagher v Gallagher [2022] EWFC 52, [2022] 1 WLR 4370, [2023] 1 FLR 120; see also his judgment in Aylward-Davies v Chesterman [2022] EWFC 4, [2022] 2 FLR 925. On 29 July 2022 he extended his analysis to the Court of Protection: Re EM [2022] EWCOP 31, [2022] 4 WLR 101. Despite his avowal in Gallagher v Gallagher that it would be his last word on the subject, he has been unable to resist the temptation to say more, justifying himself in his further endeavour (Re PP (A Child: Anonymisation) [2023] EWHC 330 (Fam) at [50]) with some very characteristic language:

‘But the flow of anonymised judgments bearing, mostly, the standard misleading and unlawful rubric (but in some instances with weird and incomprehensible variants), has continued unabated. I therefore consider that I have a responsibility to try to set out, in a final push, why I consider that routine anonymisation of the parties in financial remedy cases is likely to be unlawful.’

Very recently he has again returned to the fray in James v Seymour [2023] EWHC 844 (Fam).

The rich subtlety and the careful detail of these judgments defy short summary, and this is not the place to repeat what I have already said, first in ‘Some Sunlight Seeps In’ [2022] 2 FRJ 79, and more recently online in ‘Family Justice: Ostiis Apertis? Or a mantle of inviolable secrecy? A challenge to those who would keep the doors closed’ (available online, at https://financialremediesjournal.com/content/family-justice-ostiis-apertis-or-a-mantle-of-inviolable-secrecy-a-challenge-to-those-who-would-keep-the-doors-closed.4c5f77a599794b90b13d383037c3afd6.htm). Here I need only observe that Mostyn’s closely reasoned conclusions are securely founded in a historical analysis, as compelling as it is masterly, which refocuses attention on the great dissenting judgment of Fletcher Moulton LJ in the Court of Appeal in Scott v Scott, resoundingly vindicated when the case went to the House of Lords, and, from a later generation, disinters the almost forgotten words of Lord Blanesburgh giving the advice of the Privy Council in McPherson v McPherson [1936] AC 177.

Also to be noted is his courageous disavowal of his previous error, as he now sees it, displayed in his earlier judgments in W v M (TOLATA Proceedings: Anonymity) [2012] EWHC 1679 (Fam), [2013] 1 FLR 1513, DL v SL (Financial Remedy Proceedings: Privacy) [2015] EWHC 2621 (Fam), [2016] 2 FLR 552 and Appleton and Gallagher v News Group Newspapers and PA [2015] EWHC 2689 (Fam), [2016] 2 FLR 1. This, of course, raises a very stark question: whether Mostyn was right then, and is wrong now, or whether he was wrong then and is right now. My own view is that his most recent views are well founded in both history and principle. He is, if you like, recanting old heresy rather than descending into new heresy.

Mostyn has recently extended his analysis of the anonymity principle to other forensic contexts in a series of judgments which nonetheless are of importance for practitioners in the FRC: Re PP (A Child: Anonymisation) [2023] EWHC 330 (Fam), R (MNL) v Westminster Magistrates’ Court [2023] EWHC 587 (Admin) and TT v Essex County Council [2023] EWHC 826 (Admin) – apparently his last ever judgment in the Administrative Court. It is, if I may be so bold as to say, a merciful judgment which seems to be building up to a decision against anonymity only to swerve at the end.

As I have mentioned, Mostyn considers himself to be a good mathematician and statistician, with a particular interest in the laws of probability. The Appendix to his judgment in James v Seymour [2023] EWHC 844 (Fam) displays his mathematical skills: he sets out for ‘the algebraically minded’ the algorithm underpinning the statutory child support scheme and proceeds to deploy several pages of mathematical analysis and tabulated calculations.

His skills in relation to the laws of probability were famously displayed in a series of judgments in which he analysed the competing probabilities in relation to a past event: AA v NA and Others [2010] EWHC 1282 (Fam), [2010] 2 FLR 1173, A County Council v M and F [2011] EWHC 1804 (Fam), [2012] 2 FLR 939 and Re D (A Child) [2014] EWHC 121 (Fam). These did not find favour with the Court of Appeal when it subsequently had occasion to consider, in In re A (Children) (Care Proceedings: Burden of Proof) [2018] EWCA Civ 1718, [2018] 4 WLR 117, [2019] 2 FLR 101, the decision of Francis J in Re L (A Child) [2017] EWHC 3707 (Fam), who had, unwisely as it turned out, followed Mostyn’s analysis. The Court of Appeal (In re A at [54], [59]) was caustic and damning: ‘With the greatest respect to the erudition of Mostyn J’s arithmetical approach to the application of the “simple balance of probabilities”, I do not agree that it represents the appropriate approach.’ In following Mostyn, Francis J ‘fell into error … by the use of a “pseudo-mathematical” approach to the burden of proof’ – language which had earlier been used by the Court of Appeal in Milton Keynes Borough Council v Nulty and Others, National Insurance and Guarantee Corpn Ltd v Nulty’s Estate and Another [2013] EWCA Civ 15, [2013] 1 WLR 1183 at [35].

How the Court of Appeal whilst acknowledging his arithmetical ‘erudition’ could at the same time have described Mostyn’s approach as ‘pseudo-mathematical’ without making any attempt to challenge the mathematical correctness of his application of the laws of probability is not easy to understand. One would not, after all, describe either the laws of probability generally, or Bayes’s theorem in particular, as ‘pseudo-mathematics’. If they thought the mathematical/statistical approach was legally irrelevant, why not simply say so? What on earth did they mean by ‘pseudo-mathematical’?

Inevitably this brings to mind the famous rebuke delivered to McCardie J by Scrutton LJ in 1932. In Place v Searle [1932] 2 KB 497 at 503, McCardie had spoken approvingly of ‘the lawyer who possesses sociological vision.’ Scrutton responded witheringly. ‘I think that the less sociological knowledge is brought into the discussion of these legal questions, the better’: Place v Searle (1932) 48 TLR 428 (together with other passages critical of McCardie it is omitted from the report in [1932] 2 KB 497). McCardie’s reaction was explosive and there followed an unedifying, public dispute between McCardie and Scrutton from which neither emerged with much, if any, dignity.

Mostyn’s response to his handling by the Court of Appeal was more measured, more calculated and, it might be thought, more effective. Back in 2014 (see the case-note on Re D in the March 2014 issue of the 39 Essex Chambers Mental Capacity Law Newsletter, pp 35–37), his judgment in Re D had been commended in ‘an extremely interesting’ paper by Ian Hunt, a Chartered Statistician (Royal Statistical Society), ‘Adding a Bayes Leaf to the Law’: ‘In this case Mr Justice Mostyn handles his probability calculations with adroitness. And his vim for probabilistic argumentation is refreshing’. Subsequently, they collaborated to write as joint authors ‘Probability reasoning in judicial fact-finding’ (2020) 24 The International Journal of Evidence & Proof 75–94. It adopts an uncompromising stance. I quote from the authors’ Abstract:

‘We argue that the laws of probability promote coherent fact-finding and avoid potentially unjust logical contradictions. But we do not argue that a probabilistic Bayesian approach is sufficient or even necessary for good fact-finding. First, we explain the use of probability reasoning in Re D (A Child) [2014] EWHC 121 (Fam) and Re L (A Child) [2017] EWHC 3707 (Fam). Then we criticise the attack on this probabilistic reasoning found in Re A (Children) [2018] EWCA Civ 1718, which is the appeal decision on Re L. We conclude that the attack is unjustified and that the probability statements in the two cases were both valid and useful.’

They go on:

‘We believe the charge of “pseudo-mathematics” is clearly fallacious.’

And they conclude:

‘in some cases the best explanation of a judgment might include explicit probabilistic reasoning. But because of the ruling in Re A, whatever private inner thought processes the judge may entertain, he or she is not allowed to articulate in the judgment any reliance on the laws of probability when reaching his or her decision. What cannot be gainsaid is that there has been as a result a significant curtailment of judicial freedom in the fact-finding sphere, and that freedom is, as Winston Smith famously said in Nineteen Eighty-Four, the freedom to say that two plus two makes four.’

There matters seem to stand. What the Court of Appeal was pleased to call the ‘pseudo-mathematical’ is accepted in the Academy.

The Twitterati were amused, questioning how a judge could come to write such a piece and how the Judicial Official came to publish it.

Mostyn has now moved on, applying a probabilistic approach to identifying what degree of likelihood is required when predicting the happening of future events: see AO v LA [2023] EWHC 83 (Fam) at [25]–[49], and Financial Remedies Practice 2023–24 at paras 20.117–20.131 (note in particular the table of suggested probabilities at para 20.130). How will this fare? We can only wait to see if this also is despatched in due course by the Court of Appeal as further unacceptable ‘pseudo-mathematics’. What is the probability that it will? I fear there is a real prospect of that, though, daring to differ from Mostyn in my approach, I decline to offer a figure.

Mostyn has also been willing to criticise government policy when considered justified. In MG and JG v JF (Child Maintenance: Costs Allowance) [2015] EWHC 564 (Fam), [2016] 1 FLR 424, he reviewed the consequences of the removal of legal aid from almost all private law children cases as consequence of the Legal Aid, Sentencing and Punishment of Offenders Act 2012 having come into force on 1 April 2013. He concluded (at [20]) that:

‘it can be said that in the field of private children law the principle of individual justice has had to be sacrificed on the altar of the public debt. And … it can reasonably be predicted that the phenomenon of the massive increase in self-representation will give rise to the serious risk of the court reaching incorrect, and therefore unjust, decisions.’

It has long been the practice in the Family Division for all the judges to have various tasks, responsibilities or ‘jobs’ apart from sitting as a judge, these allocated on the basis of expertise, interest and aptitude. Thus, they usually, but not invariably (Wilson J was an earlier exception) act as Family Division Liaison Judges with pastoral and leadership responsibilities on the various Circuits. Mostyn never did. I sensed that wise self-awareness made him unenthusiastic for a task to which, despite his enormous talents, he was, truth be told, not particularly well-suited. More important, as it seemed to me, in the interests of both the Family Division and the wider family justice system, was to keep him in London where his particular talents could make the greatest contribution. I never had occasion to regret it.

His immense contributions in this regard are already the subject of detailed treatment: see my articles ‘The Origins of the Financial Remedies Court – an Insider’s View (Part 1)’ [2022] 1 FRJ 19 and ‘The Origins of the Financial Remedies Court – an Insider’s View (Part 2)’ [2022] 2 FRJ 127.

Even before the creation of the FRC, he had made a notable mark. I list his achievements:

• In 2013 I had asked Mostyn to be the judge in charge of the Royal Courts of Justice (RCJ) ‘money’ list. I chose him because of his intellectual skills, his enormous energy, and his enthusiasm for innovation. I was not to be disappointed. On 5 June 2014 he released, with my authority, a Statement on the Efficient Conduct of Financial Remedy Final Hearings Allocated to be heard by a High Court Judge whether sitting at the Royal Courts of Justice or elsewhere. Suitably revised from time to time, it remains in force.
• Also in 2013, I had asked Mostyn to undertake what became known as the Family Orders Project. It is no reflection on Mostyn’s determined leadership of a committed team that in the event this project took much longer to come to fruition than either he or I would have hoped. However, on 30 November 2017 I was able to issue Practice Guidance: Standard financial and enforcement orders and in January 2018 Class Publishing published the Standard Family Orders Handbook: Volume 1 – Financial and Enforcement by HHJ Edward Hess. Early on in the project, Mostyn had drafted the Family Orders Project House Rules. They were subject to mockery from those who professed to believe they were intended as rules to govern the application by end-users of the finalised Standard Orders and not, as was intended, the principles, as it were the design brief (equivalent to publishers’ in-house style guides), to be applied by the FOP Team in crafting the Standard Orders. They were published in the interests of transparency so that future users could see the basis upon which the FOP Team was working and, if they wished, propose changes to the design brief. I refer to the House Rules because they were a typical example of Mostyn’s thoroughness and drive for the clarity and consistency so sadly lacking in the so-called ‘agile approach’ adopted by, for example, HMCTS.
• In June 2014 I asked Mostyn to chair, jointly with Cobb J, the Financial Remedies Working Group. It reported on 31 July 2014 and 15 December 2014.

Unsurprisingly, and as I had confidently hoped, all this dedicated work by Mostyn brought about major, indeed transformative, improvements in the hearing of money cases.

Behind the scenes, I might add, his contributions were likewise invaluable. He had major input in the preparation both of the Guidance I issued on 28 February 2018: Jurisdiction of the Family Court: Allocation of Cases Within the Family Court to High Court Judge Level and Transfer of Cases from the Family Court to the High Court, and of the President’s Circular I issued on 27 July 2018, the important section dealing with ‘Private’ FDRs being included at his suggestion and indeed, as I recall, largely adopting his drafting. Mostyn’s judicial views on the matter can be found at AS v CS (Private FDR) [2021] EWFC 34, [2021] 4 WLR 68.

Mostyn’s labours in creating the FRC were, if anything, even more impressive and calculated to have the most important long-term consequences.

In his Valete, Edward Hess (and, as the Deputy National Lead Judge of the FRC, he of all people should know) rightly described Mostyn as having been ‘a powerful and irresistible force in the creation and development of the FRC.’ Mostyn would not claim the credit for inventing the idea of the FRC – that honour falls to Edward Hess and Joanna Miles, the noted Cambridge academic, for their seminal paper in November 2016 – but once I had decided in 2017 to proceed with the creation of the FRC, his involvement in the project was crucial. His appointment as the FRC National Lead Judge (with Hess as his Deputy) was announced in January 2018. Just 3 years later, after extensive piloting, the President was able to announce on 24 February 2021, in his Message from the President of the Family Division: The Financial Remedies Courts, that:

‘the Financial Remedies Courts (FRC) pilot project has now been completed … With the conclusion of the pilot phase, the FRCs should henceforth be regarded as an established and permanent part of the Family Court … The establishment of the FRC has been a success and I am therefore very pleased formally to put the project on a permanent footing within the structure of the Family Court.’

Of course, he was much assisted by the unwavering support of successive Presidents, of his Deputy, and of the many others involved during those crucial years, but the simple fact is that this vital project would never have been brought so quickly to its triumphant conclusion without Mostyn’s forceful leadership, energy and driving input.

He was largely responsible for the publication in November 2019 of what may be thought of as the founding constitutional documents of the FRC: the Financial Remedies Courts: Good Practice Protocol and Financial Remedies Courts: Overall Structure of the Financial Remedies Courts and the Role and Function of the Lead Judge. His endeavours were crowned with the publication on 11 January 2022 of their revised and elaborated replacements: Statement on the Efficient Conduct of Financial Remedy Hearings proceeding in the Financial Remedies Court below High Court Judge level, modelled on the existing High Court Statement; Financial Remedies Court: Primary Principles, replacing the previous Good Practice Protocol; and a revised version of Financial Remedies Court: Overall Structure of the Financial Remedies Court and the Role and Function of the Lead Judge. Two days later, on 13 January 2022, the up-dated Financial Remedies Court Organogram was published.

With his work done, on 26 April 2022 Mostyn stepped down as National Lead Judge of the FRC, as head of the ‘money’ list in the RCJ and as Judge in Charge of the Standard Orders, to be succeeded by Peel J. For the first time for many years, Mostyn now had no administrative or leadership responsibilities and was able to devote the remainder of his time as a judge exclusively to judging – and oh how productive those final 15 months proved to be.

One has only to contrast the state of affairs which he inherited when appointed head of the ‘money’ list in the RCJ in 2013 with the remarkable legacy he was able to hand on to his successor in April 2022 to appreciate the scale of Mostyn’s administrative achievements. It is a major part of what will prove to be a monumental and lasting legacy.

And what of the future? Mostyn sits for the last time on 28 July 2023, though an accumulated entitlement to leave not taken means that formally he does not retire until 12 December 2023. That noted diarist and reporter of gossip, Sam Seppy, tells us (see (2023) 86 Family Affairs 94 at 95) of the plans for Mostyn’s last sitting day:

‘He has his last sitting day, which will be in Wales, planned to the last hurrah, as his 90-year-old father has agreed to perform a fly past of the court centre in Swansea in his 80-year-old Auster – sauve qui peut! – and drop down to a local airstrip to whisk his son away into well-earned retirement.’

This conjures up the wonderful image of Mostyn flying up into the clouds as he retires. I am assured that the mundane reality is a little different: his father will indeed be 90, though the Auster is only 66, but after finishing at Swansea Mostyn returns for a final fortnight sitting in London.

And what of Mostyn in retirement? He will, I imagine, continue with the preparation of those hardy annuals, At A Glance and Financial Remedies Practice. And somehow I cannot see him resisting the temptations for comment, suggestions and criticism provided by the Law Commission’s recently announced financial remedies project. We shall have to wait and see.

Finally, what of Mostyn himself? What of his character?

Modesty is not an attribute one associates with Mostyn and not, one suspects, something he would ever claim for himself. He is, after all, proud to be called Tigger and labelled a Polyanna, both, it might be thought, entirely accurate characterisations. But, truth be told, false modesty is neither morally nor intellectually attractive; and the simple reality is that on any objective view Mostyn has less to be modest about than most of his legal contemporaries.

Like many very successful lawyers he can display a certain, in his case forgivable, vanity. Consider this characteristic effusion in his Foreword to the 2023 edition of the Dictionary of Financial Remedies:

‘As before, I have amused myself by getting the computer to tell me how many times I am mentioned. In 2019 it was 94 times; in 2020 it was 97; in 2021 it was 111; in 2022 it was 135; and this year I am very pleased to record that the figure has risen to 151. Again, I have further amused myself by having the computer tell me how my competitors have fared this year. The results are even more pleasing than last year.’

He goes on to record that his nearest competitors can muster only 33, 31 and 29 respectively!

A certain defensiveness and sensitivity to what he knows is a familiar criticism is perhaps apparent in what follows:

‘The customary Boolean search of Mostyn AND (criticised OR overturned OR reversed OR set-aside OR wrong OR taken leave of his senses) with a proximity filter of “on the same page” returned a positive result on 8 pages although (perhaps surprisingly) only two entries amounted to an actual criticism of a judgment of mine (NLW v ARC [2012] EWHC 55 (Fam) as to the appellate standard – a battle long lost by me; and Ipekçi v McConnell [2019] EWFC 19) as to the power to award an indemnity against any future child support calculation).’

That said, when I innocently inquired how many cases there had been in which permission to appeal one of his judgments had been given, and what percentage of the appeals had been successful, he was unable to proffer even the most approximate figures, seemingly having never kept a record.

It is a common view that the best judges are those who find themselves least often, if ever, in the Court of Appeal. The timidity which is the best prophylactic against appellate challenge does not however make for great judges. The judge who, like Mostyn, is bold, confident, clever and innovative in seeking to develop the law – and that as the career of his great predecessor McCardie J emphatically demonstrates is a proper role even for a puisne – will inevitably run into challenge. The really good judge will be taken to the Court of Appeal, but not too often, and some, but not too many of the appeals will be successful. Can it be said that Mostyn fails the test?

Speaking only of my own experience of sitting in judgment on him, while in Traversa v Freddi [2011] EWCA Civ 81, [2011] 2 FLR 272, I expressed strong criticism of some aspects of his judgment in CG v IF [2010] EWHC 1062 (Fam), [2010] 2 FLR 1790, we had no difficulty in R (ZAI Corporate Finance Ltd) v AIM Disciplinary Committee of the London Stock Exchange PLC [2017] EWCA Civ 1294, [2017] Bus LR 2139, dismissing the appeal from his judgment ([2017] EWHC 778 (Admin)). And he has even received the occasional plaudit from the Court of Appeal. In Lachaux v Independent Print Ltd [2017] EWCA Civ 1327 at [35], Davis LJ described his judgment in Lachaux v Lachaux [2017] EWHC 385 (Fam) as ‘conspicuously lucid’.

Inevitably, this takes one to his drubbing at the hands of the Court of Appeal in Rochdale Metropolitan Borough Council v KW (No 2) [2015] EWCA Civ 1054, [2016] 1 WLR 198, [2016] COPLR 77, the successful appeal from his decisions in the Court of Protection in Rochdale Metropolitan Borough Council v KW [2014] EWCOP 45, [2015] EWCOP 13. Making clear his profound disagreement with the decision in P v Cheshire West and Chester Council and Another; P and Q v Surrey County Council [2014] UKSC 19, [2014] 1 AC 896, [2014] COPLR 313, and his preference for the views of the minority in that case, Mostyn had nonetheless professed ([2014] EWCOP 45 at [19]) loyally to be following the opinions of the majority which he recognised were binding on him. The Court of Appeal did not accept that he had done any such thing. He had, they said (at [31], [33]), ‘failed to apply Cheshire West to the facts properly’ and his ‘passionate view that the legal analysis of the majority in Cheshire West is wrong is in danger of distorting his approach.’

Perhaps characteristically, Mostyn did not take this criticism lying down; within a matter of weeks, in Re CD [2015] EWCOP 74 at [38], he said this:

‘In … Rochdale … [2015] EWCA Civ 1054 at para 32 the Court of Appeal stated “even if Cheshire West is wrong, there is nothing confusing about it”. It may seem that way from the lofty heights of the Court of Appeal; and of course the literal words of the Supreme Court’s test are perfectly easy to understand. But for we hoplites who have to administer it at first instance the scope and ramifications of the test are, with respect, extremely confusing. As [counsel], instructed by the Official Solicitor for CD, rightly stated “anyone who deals with this day by day knows this is confusing” … The answers I received from the Bar when discussing [certain] scenarios belie the blithe suggestion that “there is nothing confusing” about the test. I do not accept the criticism that my approach to these cases is “distorted” by my “passionate” and “tenacious” belief that Cheshire West is wrong. Rather, it is a loyal approach which tries to apply literally and purposively the Supreme Court’s test while at the same time pointing out how confusing and curious it is, to say nothing of the cost it causes to the public purse.’

Ouch!

Perhaps inevitably there has been further controversy. In RL v Nottinghamshire CC [2022] EWFC 13, [2022] 2 FLR 1012 at [42]–[43], Mostyn observed that the well-known test used in the family courts to determine whether a previous finding of fact could be reopened – ‘there must be solid grounds for believing that the earlier findings require revisiting’ – ought to be:

‘interpreted conformably with [the decision of the House of Lords in Phosphate Sewage Company Limited v Molleson (1879) 4 App Cas 801] if a divergence from the general law is to be averted. This would mean that “solid grounds” would normally only be capable of being shown in special circumstances where new evidence had emerged which entirely changes the aspect of the case and which could not with reasonable diligence have been ascertained before.’

He went on (at [49]):

‘I naturally accept that [the existing] test is binding on me … I completely agree that on a rehearing application mere hope and speculation will never be enough to gain permission. I am merely suggesting an interpretative reconciliation between the solid grounds test and the general law such that solid grounds will normally only be demonstrated where either the fraud exception, or the special circumstances exception, is satisfied.’

This produced a magisterial rebuke from the Court of Appeal in the later case of Re J (Children: Reopening Findings of Fact) [2023] EWCA Civ 465 at [47]–[49]:

‘47. The approach in Re RL should not be followed for two main reasons.

48. A judge’s main responsibility is to decide the case in hand. The High Court and the appeal courts may also give rulings on matters of law to ensure that the law is correct, accessible to litigants and the public, and expressed in a way that is helpful to trial judges. This additional responsibility is not a vehicle to pursue a legal theory or to run the rule over binding decisions of higher courts, all the more so where the issue does not arise in the individual case. The analysis in Re RL was, and could be, of no legal effect: see Rochdale Metropolitan Borough Council v KW [2015] EWCA Civ 1054, [2015] WLR(D) 425. Decisions that reformulate a binding legal test or set up a different test are bound to be cited to trial judges and operate as a distraction and a drain on resources, as exemplified by the need for this appeal.

49. More fundamentally, it is a misconception that the time-tested approach to reopening findings of fact in children’s cases has been arrived at in ignorance or defiance of the principles of res judicata in civil proceedings. There is rightly considerable consistency in the response of all courts to attempts to relitigate … but formulations cannot be cloned from one context to another without regard to their effect. Proceedings about children take place in the context of a statutory welfare imperative and, as the present appeal shows, reopening applications may arise in a very wide range of circumstances. In order to achieve just, welfare-based outcomes in these cases, the law operates a test that differs for good reason from a test identified in another context. The formulation in Re RL originates in the decision in Phosphate Sewage Co Ltd v Molleson (1879) 4 App Cas 801, which arose from efforts to relitigate a claim in bankruptcy, but Re RL and the present case required the court to evaluate the very different considerations that arise in cases of child welfare. The applicable law is clear and there is no need to unsettle it for the sake of theoretical conformity by transposing a test devised in a different legal context.’

I have deliberately set out these passages at some length, because they seem to go to the heart of Mostyn’s judicial philosophy. A number of key issues emerge.

First, the Court of Appeal asserts that it is not the function of a puisne to ‘reformulate a binding legal test or set up a different test.’ With that, as a broad statement of principle, we can all agree, although there are many instances in the reports where a binding principle has been modified, sometimes radically, by a puisne. Moreover, is it so clear that Mostyn in Re RL in fact offended against the Court of Appeal’s precept? In his judgment, as we have seen, he accepted that the conventional test was binding on him but ventured an interpretative reconciliation which he thought would still comply with the rule of stare decisis. Where the general law – here the law of res judicata – has been developed in the highest echelons over generations it must be at least arguable that a puisne is entitled to offer an interpretation that reconciles the competing principles.

Secondly, the Court of Appeal also asserts that it is not the function of a puisne to ‘to pursue a legal theory or to run the rule over binding decisions of higher courts.’ That, if I may respectfully say so, is a much more debateable proposition, which many would not accept (I for one do not) and which, dare one say it, is falsified by history – consider, to look no further, the remarkable, and justly celebrated, judgments of puisnes such as McCardie J and Denning J. In Re RL Mostyn J questioned the validity of the conventional test, and was surely entitled to do so. Indeed, the very development of the common law depends on judges, puisne judges as well as appellate judges, identifying where an established, binding, principle needs to be revisited. Were it not so the common law would quickly become moribund.

Finally, and this is a matter of fundamental importance, there are the starkly differing views expressed by Mostyn and the Court of Appeal in relation to what may be called the exceptionalism of the family courts and the undue prevalence amongst family lawyers and family judges of what by way of shorthand I refer to as ‘desert island syndrome’. I borrow the concept from the well-known observations of Lord Sumption in Prest v Petrodel Resources Ltd and Others [2013] UKSC 34, [2013] 2 AC 415, [2013] 2 FLR 732 at [37], and in his later observations in ‘Family law at a distance’, his speech in 2106 at the At A Glance Conference, and, more recently in the ‘Interview with Lord Sumption’ [2022] 2 FRJ 167.

Mostyn’s intention as we have seen was to ‘avert’ a ‘divergence from the general law’; in other words, to minimise family law exceptionalism. In contrast, the Court of Appeal’s judgment at [49] is, it might be thought, a very strong, and, dare one say it, an all too characteristic, example of desert island syndrome.

In interesting contrast I note that, very recently, in Re C and Others (Care Proceedings: Fact-Finding) [2023] EWCA Civ 38 at [46], the Court of Appeal noted that:

‘This principle of restraint [in relation to appellate interference with case management decisions] is applied in family cases as in any other.’ (emphasis added)

Mostyn would be the first to admit that, once upon a time, not least in relation to anonymity, he suffered from the syndrome but, as already noted, his more recent judgments on the topic evince a profound rejection of Family Court exceptionalism – and here he is surely in good company. After all, when on 28 October 2021 the President published the outcome of his Transparency Review, Confidence and Confidentiality: Transparency in the Family Courts, he specifically asserted (at para 22) that the Family Court can no longer continue to be ‘an exception from the ordinary imperative for open justice ... it is necessary for the court to regard openness as the new norm … there needs to be a major shift in culture and process.’

One day someone with a sufficiently uncluttered mind and an interest in what French historians would call ‘histoire des mentalités’ will study this interesting phenomenon of Family Court exceptionalism in its origins and its tenacious longevity. This History of the War of the Desert Islands will I fear be illustrated with all too many choice examples of egregious Family Court exceptionalism.

As long ago as 1959, in In re Hastings (No 3) [1959] Ch 368 at 377–379, Vaisey J lamented ‘how hardly this idea of the separate courts dies’ despite the Judicature Acts in the 1870s.

‘The expression “The Court of Chancery” is constantly heard, yet it is three generations since it existed as a court. “The Court of Queen’s Bench” is referred to in the same way: but there is now only one court – the High Court of Justice … If it is thought that there is some kind of emanation of the Chancery spirit which can overrule the decisions of the Queen’s Bench, or some special inspiration of common sense which allows a judge of the Queen’s Bench to say that the decisions in the Chancery Division are wrong, that is complete illusion.’

It is now over 60 years since that was said, but in the family courts the illusion continues to linger.

Dare I suggest that a revealing insight into the ‘mentalités’ is the Court of Appeal’s characterisation of Phosphate Sewage as a bankruptcy case – contrast Lord Diplock’s use of it in Hunter v Chief Constable of the West Midlands Police and Others [1982] AC 529, where the question – utterly remote from bankruptcy – arose out of criminal proceedings. To characterise Phosphate Sewage as a bankruptcy case is, of course, as accurate as to characterise Gillick v West Norfolk and Wisbech Area Health Authority [1986] AC 112 as being a medical case about contraception or Donoghue v Stevenson [1932] AC 562 as being a case about the sale of sealed containers. But does it not rather miss what might be thought to be the real point?

There are encouraging signs that the tide is starting to turn. The recent decision of the Court of Appeal in Abbasi v Newcastle upon Tyne Hospitals NHS Foundation Trust [2023] EWCA Civ 331 marks, both in tone and in substance, an important and highly significant retreat from Family Court exceptionalism. The court referred pointedly (at [2]) to the ‘the modern practice in the Family Division of the High Court of granting indefinite anonymity orders’ – and the comment was not intended to be complimentary.

One day, this whole idea of Family Court exceptionalism will come to be seen and be accepted as the unhistorical and unprincipled dogma it is. Mostyn will then be seen to have been on the right side of history.

A judge with Mostyn’s clarity of analysis and great intellect is always going to be prey to the feeling that some of his judicial superiors are not his intellectual equals and that on occasions even those who he would accept are his intellectual equals have fallen into error. That is in the nature of the human condition, and judges are not super-human. A judge is perfectly at liberty – indeed, it may on occasions be his duty – to express himself frankly about the perceived error of others, so long as he observes, as Mostyn does, the common decencies of intellectual disputation and, critically, plays by the ‘rules of the game’, in other words loyally applies the rules of stare decisis in following decisions by which he is bound. The proper approach is indeed that surely properly followed by Mostyn himself in Hasan v Ul-Hasan, decd and Another [2021] EWHC 1791 (Fam), [2022] Fam 1, [2022] 1 FLR 1033.

I take my leave of one who I do not hesitate to say is a great lawyer and a great judge by posing, even if I do not proffer any definitive answer, a question which inevitably raises comparison between Mostyn and his equally distinguished predecessor McCardie J. What in the modern court system as it was created 150 years ago by the Judicature Acts is the proper function and role of the puisne? Views on this will inevitably differ, though for my own part I believe a puisne is entitled, for example, to rattle cages, to denounce injustice and to develop the law even in radical and unprecedented ways if that is required by the call of justice and the demands of the judicial oath. Did McCardie and Mostyn overstep the bounds? No!