Mark Keenan

Mark is a senior Partner in Mishcon Private with expertise in Private Wealth Disputes, specialising in complex multi-jurisdictional trust disputes and succession disputes, with a particular focus on inter-family issues. Mark is a leading advisor in complex asset-tracing and recovery work involving offshore jurisdictions.

Mark has significant experience in advising private individuals and trustees on cross-border inheritance disputes, Will disputes, Inheritance Act claims, Court of Protection applications, estate administration issues, breach of trust and proprietary estoppel claims.

Mark is a recognised leader in his field. Chambers High Net Worth Guide 2025 describes Mark as "fantastic; a litigator's litigator, he is calm, hugely knowledgeable and has excellent tactical nous". "He manages to mix tremendous flair with the more mundane aspects of the law. So even when a long-term case is perhaps at a hiatus, he can breath new life into it. He creates hope and results."

Mark also sits as Division head with responsibility for the firm's Private Wealth Disputes and Family teams.

Legal 500 rankings highlighted Mark as "an outstanding litigator, with an unparalleled tactical feel, a legend in the field".

Spear's Tax & Trust Advisers Index 2025 lists Mark as a Top Recommended Contentious Trust Lawyer and Who's Who Legal list him as a Global Leader in his field.

Mark is a member of the Association of Contentious Trust and Probate Specialists (ACTAPS), the Society of Trust and Estate Practitioners (STEP) and the International Fraud Group (IFG). The IFG is a global network of specialist fraud lawyers across 14 countries focused on securing injunctions, asset recovery and trust busting remedies in key offshore jurisdictions.

He is a professional Deputy of the Court of Protection.

Key Experience

• Acting in a multi-billion pound dispute for high-net worth individuals in a global fraud and cross border estate dispute across numerous jurisdictions, including England, USA, Monaco, Panama, Latvia, Switzerland and Cyprus.
• Acting for beneficiaries in a complex high value multi-jurisdictional trust dispute (including G v SG Kleinwort Hambros [2023] JCA 088).
• Bathurst (Wesley) v Chantler and Ors [2018] EWHC 21 (Ch): Representing Lady Bathurst in relation to issues of assent and construction of a trust created by a Statutory codicil.
• MN v OP and Ors [2017]: Regarding variation of trusts and anonymity orders.
• Dellal v Dellal and Others [2015] EWHC 907 (Fam): Acting for various members of the Dellal family in a significant, high profile family dispute brought under the Inheritance (Provision for Family and Dependants) Act 1975.
• Gorbunova v Berezovsky [2013] EWHC 771 (Ch): Mark represented Helena Gorbunova following the breakdown of her relationship with Boris Berezovsky and his subsequent death, which included multi-faceted claims in the Family and Chancery division, including securing multi-jurisdictional injunctions against him. Following Mr Berezovsky's unexpected death, this involved advising on multiple claims relating to his estate and ancillary litigation.
• Mark acted for siblings in a long running inheritance dispute to determine whether assets held in a Liechtenstein foundation and other assets form part of their late father's estate, in a claim which involved Sharia law and the laws of Switzerland, Liechtenstein and Monaco.
• Stow -v-Stow [2008] EWHC 495 (Ch): Mark acted for Mrs Zoe Stow in a complex international trust and succession dispute.
• Gill v Woodall and Others [2010] EWCA Civ 1430: Mark represented Dr Christine Gill in the Court of Appeal who upheld the decision to overturn a will leaving the RSPCA a £2.35m farmhouse and land.
• Gill v RSPCA [2009] EWHC 2990 (Ch): In October 2009 the High Court in Leeds had ruled that the will leaving the family 's farm to the RSPCA was invalid. Dr Gill also succeeded in her alternative claim to the farm under the doctrine of proprietary estoppel.
• Martin v Triggs Turner Barton and Ors [2009] EWHC 1920 (Ch) and also see Martin v Triggs Turner Barton and Ors [2008] EWHC 89 (Ch): Mark represented Dr Alison Martin in her successful claim against TWM solicitors in which it was held that her late husband 's Will had not been drafted in accordance with his instructions. Dr Martin also succeeded in her claims that the solicitors had given negligent advice to her concerning the tax treatment of national savings certificates held by her late husband 's estate and her entitlement to a widow's pension.
• Mark was appointed by the court to administer a multi-million pound disputed estate. The case involved allegations of forgery lack of due execution and want of knowledge and approval and settled at a multi-party mediation.
• Mark has been appointed to act as a Professional Deputy of the Court of Protection for a young woman who is incapable of managing her financial affairs. Mark had represented the young woman in her negligence action against her local Health Authority which settled out of court.
• Franks v Sinclair [2006] EWHC 3365 (Ch): Mark acted for the successful Defendants, in their challenge to the validity of their late grandmother's Will. The court found that Mrs Franks, who had testamentary capacity, did not know and understand the contents of the Will which had been prepared for her by her son who was a solicitor.

Career History

Partner, Mishcon de Reya LLP
Qualified, Mishcon de Reya LLP
University of Westminster, LLB (Hons)