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Hendersons - Barristers' Chambers

Jack Castle

“Jack is intellectually strong and gets to grips with a matter very quickly. He is a confident advocate and has a good manner with judges when put on the spot.”

Legal 500 2025


Call
2018

Jack has a busy practice in line with Chambers’ expertise, encompassing commercial, financial services, product liability, employment, procurement and public law/human rights. He acts in individual and group claims, and is ranked as a “Rising Star” in Administrative Law and Human Rights and Employment by the Legal 500.

His work ranges from matters concerning the identity of the pseudonymous founder of Bitcoin ‘Satoshi Nakamoto’ and intellectual property rights in its blockchain (one of The Lawyer magazine’s Top 20 Cases of 2024) to the classification of Universal Credit for the purposes of EU social security coordination and the ongoing power to refer questions to the CJEU (currently on appeal to the Supreme Court), and acting for a major German manufacturer in the NOx emissions litigation. Many of his cases involve issues of retained EU/assimilated law and the impact of the UK-EU Withdrawal Agreement. He is currently instructed in a number of applications to the European Court of Human Rights.

Jack also appears regularly as sole counsel in the High Court, and has particular experience of urgent pre-action and interim relief, including proprietary and freezing injunctions, particularly in commercial, breach of confidence and employee competition cases. He also frequently appears in administrative appeals before the Upper Tribunal, in Employment Tribunals and the county courts. A number of his cases have been reported on by the national press. Clients include individuals, corporations, public authorities, finance houses, NGOs and central government (as a member of the Attorney General’s ‘C’ Panel).

He is an editor of Practical Lending and Securities Precedents covering assignment and participation of loans, of the judicial and statutory review chapters of Butterworth’s Civil Court Precedents, and of the chapter on FCA regulation and authorisation in Consumer Credit Law and Regulation (2024).

Previously Jack was a Judicial Assistant in the Commercial Court, chiefly to Mrs Justice Cockerill (judge in charge of the Commercial Court), and a Visiting Lecturer in European Law at City Law School, University of London.

Before the bar Jack worked in the commercial art world. He is a trustee of Poetry London.


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Expertise


Commercial

Jack’s commercial practice includes complex disputes arising out of banking and finance, frauds, intellectual property and cryptocurrency, as well as confidential information, restraint of trade and general contractual matters.

Many of his cases arise in the context of partnerships, joint ventures or the employment relationship. He also acts in cases involving secret commissions, bribery, breach of fiduciary duty and unjust enrichment.

He frequently acts in applications for urgent and pre-action injunctions, including proprietary and freezing injunctions, in areas from team-move litigation to real property investments.

He is also instructed in commercial matters raising other areas of law, particularly public law and financial regulation.

In 2021 Jack was a judicial assistant in the Commercial Court, chiefly to Cockerill J (Judge in charge of the Commercial Court). He is an editor of Practical Lending & Security Precedents.

Representative cases

grid list
  • Wright & Oths v BTC Core & Oths

    Instructed in a claim concerning the identity of the pseudonymous founder of Bitcoin ‘Satoshi Nakamoto’ and intellectual property rights in its blockchain. This includes the ‘identity issue’ trial deciding the identity of Satoshi – [2024] EWHC 1198 (Ch) – one of The Lawyer magazine’s Top 20 Cases of 2024 (led by Terence Bergin KC).

  • Wright v McCormack [2024] EWHC 1735 (KB)

    Instructed in an application for a freezing order based on allegations that costs orders had been procured by fraud (led by Adam Baradon KC).

  • Advice on fraud by an employee and ownership of intellectual property

    As sole counsel, advised a large manufacturing concern concerning apparently fraudulent payments made by employees of over £600,000, potential computer hacking by those employees, and a dispute over intellectual property rights in software made during the course of employment.

  • Advice on jurisdiction and choice of law

    Instructed to advise on the correct construction of a contract for financial services with competing jurisdiction and choice of law clauses in favour of both English and Lithuanian law and courts.

  • Breach of restrictive covenant and misappropriation of Facebook accounts

    Instructed as sole counsel in the High Court in a claim involving a number of employees who retained work Facebook accounts following resignation in order to start a new competing business.

  • Partnership dispute

    Instructed as sole counsel in the High Court in a long-running dispute concerning a partnership formed to invest in residential property, involving allegations of misuse of partnership assets and breach of constructive trust. Jack secured urgent, without notice proprietary relief to prevent imminent disposal of partnership property ([2023] EWHC 2647 (Ch)).

Public and Regulatory

Jack undertakes the full spectrum of public law work as both junior and sole counsel. He is ranked in the Legal 500 for his work in Administrative Law and Human Rights.

His public law work spans a variety of areas, from regulation of financial services and healthcare to freedom of information, data protection and environmental law. This includes judicial review and statutory and administrative appeals processes, as well as civil claims against public authorities and the overlap between public and other areas of law.

Recent instructions include: applications to the European Court of Human Rights concerning discrimination based on marital status and legislative intervention in ongoing proceedings, acting for the Welsh Government in the Covid Inquiry, advising a well-known trade union on regulatory matters and freedom of speech concerns, judicial reviews relating to protected species, biodiversity and matters relating to renewable energy subsidies (see ‘Environmental’), a challenge to the lawfulness of inspections by a healthcare regulator and linked A1P1 damages claim (led by Patrick Green KC) and an important appeal regarding the classification of Universal Credit for the purposes of the EU social security coordination rules and the power to refer questions to Luxembourg post-Transition Period (led by Thomas de la Mare KC, permission to appeal to the Supreme Court granted).

He has a particular interest in social security and welfare benefits. He regularly represents claimants in the Upper Tribunal and accepts instructions on a publicly funded or pro bono basis.

Representative cases

grid list
  • Simkova v Secretary of State for Work and Pensions [2024] EWCA Civ 419

    Acting for a Slovakian national in an important appeal concerning entitlement to the child element of Universal Credit, raising issues concerning the interaction of Universal Credit with EU Regulation 883/2004 on the coordination of social security systems (led by Thomas de la Mare KC). Jack represented Ms Simkova before the Upper Tribunal as sole counsel ([2023] UKUT 44 (AAC)). Permission to appeal to the Supreme Court has been granted.

  • C v A Regulator

    Instructed in a commercial judicial review involving alleged apparent bias by a regulator’s inspector and a linked A1P1 damages claim (led by Patrick Green KC).

  • R(L) v Service Complaints Ombudsman for the Armed Forces [2024] EWHC 1094 (Admin); [2024] A.C.D. 76

    Appeared as sole counsel for the interested party, the Ministry of Defence, in a judicial review concerning the jurisdiction of the Service Complaints Ombudsman for the Armed Forces.

  • Advice on bulk data collection

    Advised a public authority on bulk data collection and the impact of Article 8 ECHR and UK GDPR (led by Christopher Knight).

  • Secretary of State for Work and Pensions v MA [2024] UKUT 131 (AAC); [2024] P.T.S.R. 1243

    Appeared as sole counsel in an Upper Tribunal appeal concerning whether selling stolen goods is considered “work”, and if money obtained therefrom is “income”, for the purposes of entitlement to income-related Employment and Support Allowance.

  • Re: Regulation of Advertising

    Instructed, as sole counsel, by a well-known trade union in potential judicial review proceedings arising out of potential regulatory action relating to advertising, raising issues of jurisdiction (including a “precedent fact” challenge) and Article 10 ECHR. The regulator dropped its investigation following pre-action correspondence.

Financial Services

Jack is regularly instructed by major UK lenders for his expertise in financial services, as well as representing investors and customers.

This includes disputes and advisory work concerning, for example, the execution and enforcement of secured and unsecured loans, asset financing, guarantees, financial product mis-selling, secret commissions and fiduciary duties owed by brokers and advisors, and matters involving suspension of bank accounts due to fraud and/or money laundering.

He has a particular interest in financial regulation, including matters involving compliance with FSMA, the RAO, the Financial Promotions Order, the Consumer Credit Act 1974, and civil consequences for regulatory breaches under FSMA.

In 2022 he was seconded to the FCA to assist with investigations into the adequacy of advice given to customers transferring out of Defined Benefit pensions.

Jack is editor of the ‘Assignment & Participation of Loans’ chapter of Practical Lending & Security Precedents and has recently completed a chapter on FCA regulation and authorisation in the consumer credit sphere.

Representative cases

grid list
  • Advice on jurisdiction and choice of law

    Instructed to advise on the correct construction of a contract for financial services with competing jurisdiction and choice of law clauses in favour of both English and Lithuanian law and courts.

  • Appeal against "fit and proper" assessment for AML purposes

    Instructed as sole counsel by HMRC defending an appeal against the “fit and proper person” decision under the Money Laundering, Terrorist Financing and Transfer of Funds (Information on the Payer) Regulations 2017.

  • A v B Ltd and C

    Instructed as sole counsel in a claim against a claims management company alleging breach of the general prohibition and seeking compensation under section 26 FSMA.

  • Advice on s.138D action and FOS complaint

    Advising an investor on potential breaches of the FCA Handbook and the FPO by an Appointed Representative with a view to recovering their investment in a failed £2m property venture.

  • FCA Defined Benefits Pensions Enforcement

    Assisted the FCA in a large-scale enforcement action arising out of inadequate provision of advice surrounding transfers out of defined benefits pension schemes.

  • Claim against major online bank

    Instructed as sole counsel defending a major online bank against an alleged breach of the Quincecare duty and breach of the Payment Services Regulations 2017 arising out of an alleged authorised push-payment fraud.

Group Actions

Jack has assisted leading counsel on procedural and substantive aspects of domestic and international group actions.

He has experience of group claims involving financial mis-selling, medical devices and medications, consumer rights, environmental disasters and international tort claims, including what is reportedly the biggest group action in English legal history arising from the collapse of the Fundão dam in Brazil.

This has included issues ranging from choice of law and management of the claimant group to novel points in the law of tort, parent company liability, and the immunity of international organisations.

He has also advised and assisted in advising on the preliminary stages of a number of group actions, including considerations of the most suitable substantive causes of action to certain group claims, organisation of the claimant cohort, strategy, tactics, and potential funding issues.

Representative cases

grid list
  • Mercedes-Benz NOx Emissions Group Litigation

    Instructed for the Mercedes-Benz Defendants in what is thought to be the largest GLO proceedings currently before the English courts. Jack recently appeared (led by Helen Davies KC) in the “KBA Trial”, concerning whether the English court is bound by decisions taken by the Kraftfahrt-Bundesamt pursuant to the EU regime before, during and post-Brexit.

  • Medical device group action

    Instructed by the manufacturer in a claim concerning a permanent birth control device (led by Toby Riley-Smith KC).

  • A consumer rights group action

    Instructed to advise on a group claim involving deception by traders relating to past usage of second-hand goods raising complex issues of European-derived law (including whether certain domestic legislation is an implementation of an EU directive and indirect effect). This included advising on the suitability of certain causes of action for group litigation and organisation of a claimant cohort, as well as strategy, merits and quantum (led by Nazeer Chowdhury).

  • Group action concerning mis-selling of property investments

    Assisted in advising the claimant group following the collapse of a US property investment scheme, on issues including forum and choice of law, attribution of knowledge to a company, joint liability in tort and practical issues concerning how to arrange the claimant group.

Employment

Jack regularly acts in High Court employment-related commercial matters involving team moves, misuse of confidential information, breach of contract and restrictive covenant, and intellectual property issues arising in this context, including applications for interim injunctive relief and civil frauds involving diversion of company funds and property.

He also appears as sole counsel in statutory Employment Tribunal claims for unfair dismissal, whistleblowing, discrimination, failure to make reasonable adjustments, holiday pay and unlawful deduction of wages. This includes potential lifetime loss of earnings cases with values exceeding £750,000.

He has further experience of the TUPE regime, worker status, the agency workers regulations, pensions and bonus disputes, and public law issues arising in employment matters. He represents both employees and employers.

He is also instructed on non-employment discrimination matters, including relating to provision of services and education, and novel claims arising out of the employment relationship.

Jack has been ranked in the Legal 500 for a number of years for his employment work.

Representative cases

grid list
  • Hilton Foods Solutions v Wright [2024] I.C.R. 862; [2024] I.R.L.R. 532

    Acted successfully as lead counsel in the EAT in a matter concerning the meaning of “sought” to take parental leave in the Maternity and Parental Leave etc. Regulations 1999.

  • Breach of restrictive covenant and misappropriation of Facebook accounts

    Instructed as sole counsel in the High Court in a claim involving a number of employees who retained work Facebook accounts following resignation in order to start a new competing business.

  • R(L) v Service Complaints Ombudsman for the Armed Forces [2024] EWHC 1094 (Admin); [2024] A.C.D. 76

    Appeared as sole counsel for the interested party, the Ministry of Defence, in a judicial review concerning the jurisdiction of the Service Complaints Ombudsman for the Armed Forces.

  • Team move in the recruitment industry

    Instructed, as sole counsel, in a High Court pre-action injunction and claim involving misuse of confidential information on behalf of (and diversion of business to) a competitor, and breach of restrictive covenant.

  • Breach of director's duties and diversion of profits

    Instructed, as sole counsel, in a High Court matter alleging appropriation of significant sums from the business by the company secretary and their accomplice, listed for an 8-day trial in 2024. Settled at mediation.

  • Claim for failure to properly report to pension scheme

    Instructed in an action for negligent failure by an employer to give a correct report of the reason for an employee’s dismissal to the pension scheme, leading to loss of pension from that scheme (led by Adam Heppinstall KC).

EU and International

Jack has extensive experience of international law, European Union law and retained EU law matters as they arise across his areas of practice.

Before joining chambers Jack was Visiting Lecturer in EU Law at City, University of London, and has been involved in a number of cases raising EU law issues as both sole and junior counsel, ranging from social security coordination to consumer rights, database rights (in the context of the Bitcoin blockchain) and employment law matters. He is also involved in a matter concerning the interpretation of the power to refer questions to the CJEU under Article 158 of the Withdrawal Agreement.

He is also frequently involved in matters concerning the ECHR, in particular Articles 6, 8, 14 and Article 1 of the First Protocol, generally in regulatory and social security contexts. He is currently involved in a number of applications to the Strasbourg court.

Representative cases

grid list
  • Mercedes-Benz NOx Emissions Group Litigation

    Instructed (led by Helen Davies KC) in the “KBA Trial”, concerning whether the English court is bound by decisions taken by the Kraftfahrt-Bundesamt pursuant to the EU regime before, during and post-Brexit.

  • Wright & Oths v BTC Core & Oths

    Instructed in a claim concerning the identity of the pseudonymous founder of Bitcoin ‘Satoshi Nakamoto’ and intellectual property rights in its blockchain. This includes the ‘identity issue’ trial deciding the identity of Satoshi – [2024] EWHC 1198 (Ch) – one of The Lawyer magazine’s Top 20 Cases of 2024 (led by Terence Bergin KC).

  • C v A Regulator

    Instructed in a damages claim under A1P1 and linked judicial review alleging apparent bias in the regulatory process (led by Patrick Green KC).

  • Hilton Foods Solutions v Wright [2024] I.C.R. 862; [2024] I.R.L.R. 532

    Acted successfully as lead counsel in the EAT in a matter concerning the meaning of “sought” to take parental leave in the Maternity and Parental Leave etc. Regulations 1999.

  • Re: Regulation of Advertising

    Instructed as sole counsel by a well-known trade union in potential judicial review proceedings arising out of potential regulatory action relating to advertising, raising issues of jurisdiction and Article 10. The regulator dropped its investigation following pre-action correspondence.

  • Simkova v Secretary of State for Work and Pensions [2024] EWCA Civ 419

    Acting for a Slovakian national in an important Court of Appeal matter concerning entitlement to the child element of Universal Credit, raising issues concerning the interaction of Universal Credit with EU Regulation 883/2004 on the coordination of social security systems (led by Thomas de la Mare KC). Jack represented Ms Simkova before the Upper Tribunal as sole counsel ([2023] UKUT 44 (AAC)).

Environmental

Jack has experience of environmental cases in public, private and criminal law contexts, including habitat and species protection, climate change, nuisance, rights to water, drainage and flooding, as well as of the regime concerning access to environmental information.

He recently assisted in advising on a potential public law challenge to the regime of subsidy for low-carbon electricity generation.

Jack is a pro bono member of the Environmental Law Foundation.

Representative cases

grid list
  • Claim in noise nuisance

    Instructed in a claim between long leaseholders alleging noise nuisance due to defective sound insulation installed before either leaseholder was resident.

  • Dispute concerning “feed-in” tariffs

    Instructed by a “Big Six” energy supplier in relation to a dispute concerning renewable energy feed-in tariffs.

  • Advice on challenging adoption of a local plan

    As sole counsel, advised a resident on a potential public law challenge to adoption of a local plan due to the presence of EU-protected species.

  • Advice on response to planning application

    As sole counsel, advised residents on public law grounds to oppose grant of planning permission, including incompatibility with the local plan, loss of open space and overloading of local amenities, drainage/flooding issues and inadequate consideration of impacts on protected species, habitat, and climate change objectives.

  • Advice on drainage and flooding issues

    Assisted in advising on potential easements to drain into neighbouring land and liability for flooding.

Procurement and Subsidy Control

Jack has a particular interest in procurement, and acts for contracting authorities and economic operators in procurement and subsidy control matters.

In 2020 he was seconded to the Government Legal Department’s ‘Covid Cell’, advising on a variety of important procurement and state aid matters relating to the Covid-19 pandemic, including procurement of mass testing capacity and vaccines.

He is a procurement specialist member of LexisNexis’ Q&A Panel.

Representative cases

grid list
  • Advising an economic operator on a £150m procurement

    Advising an economic operator in a potential challenge to the marking and award of a contract in the justice sector.

  • Advising on the TCA and Northern Ireland Protocol

    Advising central government on the subsidy implications of grants to improve social housing, under the TCA, Subsidy Control Act 2022 and Northern Ireland Protocol.

  • Advising Government departments on Covid-19 response

    Seconded to the Government Legal Department to advise a range of Government departments on procurement, state aid and commercial law issues associated with the UK’s pandemic response.

  • A financial services group action

     Assisted in advising on a potential state aid and/or public law defences to the setting of interest rates on certain financial products.

 

What the directories say


“Jack is intellectually strong and gets to grips with a matter very quickly. He is a confident advocate and has a good manner with judges when put on the spot.”
Legal 500 2025

‘Jack is a very effective cross-examiner and an impressive, unperturbed advocate.’
Legal 500 2024

Instructing Jack Castle

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Appointments
  • Attorney General’s Panel of Junior Counsel to the Crown, C Panel (2023)
  • Centre for Women’s Justice, Legal Reference Panel
  • Panel Member, Advocate
Publications
  • Contributing Editor of ‘Judicial Review, Statutory Review and Habeas Corpus’ in Butterworth’s Civil Court Precedents
  • Author of the ‘FCA Authorisation’ chapter in Consumer Credit Law and Regulation (2024)
  • Editor of ‘Assignment & Participation of Loans’ in Practical Lending & Security Precedents
  • Contributor to Lexis®PSL Public Law
  • Procurement Specialist Contributor to LexisNexis Q&A panel
Memberships
  • ALBA
  • COMBAR
  • Environmental Law Foundation
  • Employment Lawyers Association
  • Financial Services Lawyers Association
  • Young Public Lawyers Group
Education

Education

  • BA English Literature, Bristol University, First Class
  • MSt. English Literature Post-1900, University of Oxford, Distinction
  • GDL, City Law School, University of London, Distinction
  • BPTC, City Law School, University of London

Scholarships

  • Major Scholarship (BPTC), Inner Temple (2017)
  • Duke of Edinburgh Entrance Award, Inner Temple (2017)
  • Postgraduate Scholarship (BPTC), City Law School (2017)
  • Kalisher Trust Advocacy Training Programme (2017)
  • Exhibition (GDL), Inner Temple (2016)
  • Postgraduate Scholarship (GDL), City Law School (2016)
Regulatory Information

All members of Chambers are registered with the Bar Standards Board of England and Wales. For our standard contractual terms click here.

For more information about the way barristers at Henderson Chambers work, including our fee transparency statement and our complaints process, please click here.

Bar Council Number: 70906

VAT Registration Number: 356025609

Legal Status: Barrister

Professional Insurance: All members of Chambers have professional liability insurance provided by the Bar Mutual Indemnity Fund Ltd. Territorial coverage is world-wide and subject to the term of the Bar Mutual. Click here for details.

Regulated by the Bar Standards Board.

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