Roger Stewart KC and Theo Barclay Secure Summary Dismissal of £20m Loss of a Chance Claim in High Court: Cohen v Morrison & Ors
On Monday, the High Court handed down judgment in Cohen v Morrison…
Legal 500
“Theo is incredibly bright, but also very friendly and approachable. He turns things around very quickly and is a joy to work with”
Theo specialises in commercial litigation. His cases have featured in The Lawyer’s Top 20 Cases/Appeals for 2021, 2024, 2025 and 2026. He was nominated by Legal 500 as Intellectual Property Junior of the Year 2025.
He is ranked in the legal directories in international arbitration (“Written advocacy is terrific… Pleasure to work with”), intellectual property (“detail orientated, personable, and a brilliant advocate“), sports law (“…has a fantastic understanding of the nuances of sports law“), professional negligence (“He is definitely a star of the future”) and costs and litigation funding (“…lovely to work with and really knows costs and procedure…”).
Theo’s commercial litigation and arbitration practice is wide-ranging, spanning intellectual property, civil fraud and professional negligence . His sports law practice is similarly broad, including player/agent disputes and commercial litigation in a sports context. He also specialises in the law of costs and litigation funding, with a particular focus on funding issues in heavy commercial litigation and solicitor/client matters.
He has appeared in leading cases across his areas of expertise, including in the Supreme Court and Court of Appeal. His recent instructions include appearing in the Supreme Court for the successful appellants in Iconix v Dream Pairs, a leading case on trade mark infringement; appearing in the Court of Appeal in Julia Mazur & Ors v Charles Russell Speechlys on who is entitled to conduct litigation; acting for over 1 million claimants in the NOx Emissions Group Litigation; representing Liverpool Football Club in three major cases in the Commercial Court; and acting for the claimant on litigation costs issues in Skatteforvaltningen v Solo Capital Partners LLP (a £1bn + fraud claim).
Theo is one of the editors of the Costs and Litigation Funding supplement to the White Book 2025 and 2026 and has lectured on commercial law at City University, London.
In his spare time, Theo has written a book on UK politics (Fighters and Quitters: Great Political Resignations, Biteback 2018) and contributed chapters on Joan of Arc, Henry II and George Canning to The Generals (Hodder and Stoughton, 2026), Kings & Queens of England (Hodder and Stoughton, 2023), The Prime Ministers (Hodder and Stoughton, 2022).
Further details about Theo’s practice areas are set out below.
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Theo’s is regularly instructed, led and unled, to act in high value commercial disputes in the Commercial Court, Circuit Commercial Court, Chancery Division and in international and domestic arbitrations.
He has been ranked in Legal 500 as a “rising star” for Commercial Litigation, described as “…outstanding. Smart, diligent, hard-working. Absolutely will go as deep into the subject matter as necessary to find the answers and to be prepared…excellent on his feet“.
Theo’s commercial practice encompasses insurance, civil fraud, banking & financial services, intellectual property disputes, sports disputes, litigation funding claims and high-value professional negligence claims, as set out in the sections below.
He has particular experience acting in urgent claims for freezing and proprietary injunctions (domestic and worldwide), including in support of arbitration or foreign seated litigation and at the enforcement stage.
Current and recent cases include:
Theo’s intellectual property practice is focused on trade mark law, copyright infringement, registered designs and passing off. He has been instructed in several of the leading appellate cases in the field, alongside disputes in the Chancery Division and Intellectual Property Enterprise Court. He also appears in registration cases in the UK Intellectual Property Office.
In 2025 he was nominated for the Legal 500 Intellectual Property Junior of the Year award.
He is ranked as Leading Junior in Legal 500 and Chambers & Partners for Intellectual Property law, who describe him as “detail orientated, personable, and a brilliant advocate” as well as “collaborative and strategic with a firm grip on the legal issues” with “a real awareness of the commercial background and client relationships”.
Theo was recently instructed as junior counsel to the successful appellants in the leading Supreme Court case Iconix v Dream Pairs [2025] UKSC 25, now the leading authority on the similarity and confusion tests in trade mark law.
In 2023 he appeared in the Court of Appeal in Combe v Dr Wolff [2022] EWCA Civ 1562, which is the leading case on acquiescence in trade mark law.
Other current and recent instructions include:
Theo’s has appeared in several recent leading fraud cases, including as junior counsel in B.V. Nederlandse Van Eiprodukten v Rembrandt Enterprises[2019] EWCA Civ 596, the landmark Court of Appeal authority on the test for inducement in fraudulent misrepresentation (led by Guy Morpuss KC); and
He also has experience of various interlocutory applications in a civil fraud context, including of applications for worldwide freezing orders in support of litigation and arbitration.
Current and recent fraud cases include:
Theo is building a strong domestic and international arbitration practice, with a range of claims under a variety of institutional rules, including ICC, SIAC, LCIA, Swiss Rules and FA Rule K.
He is ranked as a Leading Junior in international arbitration by the Legal 500. His written advocacy is praised as “terrific“, “well structured and clear” and he is described by clients as “very responsive and pragmatic” and a “pleasure to work with“.
He has particular experience:
He also has expertise on the principles of awarding costs of arbitration, having acted in Martin v Harris, a High Court appeal on costs under the Arbitration Act 1994.
Featured arbitration cases:
Theo is ranked as a Leading Junior for costs litigation in Chambers & Partners and the Legal 500 and is described as:
“Theo has a sound knowledge of subject matters and his written work and advocacy skills are exceptional.”
“Theo is incredibly bright, but also very friendly and approachable. He turns things around very quickly and is a joy to work with.”
He recently appeared in Therium Litigation Funding v Bugsby Property LLC and Omni Bridgeway v Bugsby Property LLC, the first post-PACCAR cases in the Commercial Court concerning the enforceability of litigation funding agreements.
His practice covers the whole spectrum of costs law, including:
He is also regularly instructed:
His current and recent instructions include:
Theo has a wealth of experience in professional liability claims, having advised and acted in claims involving tax advisors, solicitors, auditors, accountants, surveyors, construction project managers and engineers.
He is ranked as a leading junior in professional negligence by Legal 500: “Theo is a slick and accomplished trial advocate, always prepared for every eventuality with an uncanny ability to read the court room. He is destined for greatness.”
In his professional liability practice, he acts for both claimants and defendants in cases in the county courts and the High Court.
Featured professional liability cases:
Theo is very experienced in advising and acting in professional liability claims against legal professionals. He acts for both Claimants and Defendants.
He has experience in the full range of solicitor and barrister liability claims, including lost litigation, under settlement, Limitation Act claims, domestic and international conveyancing negligence and claims arising out of personal injury litigation.
He has also acted in claims against solicitors relating to non-contentious transactions that have failed, such as business sales and wills claims.
Current and recent instructions include:
Theo has extensive experience of claims involving accountants and auditors, which has included the following:
Current and recent cases include:
Theo has experience acting in claims involving auditors, brokers, actuaries, IFAs and tax advisors.
He has a strong background in investment advice work, having worked for three years on behalf of the Financial Conduct Authority as a ‘skilled person’ under s.166 FSMA, reviewing compensation claims made by SMEs that had been miss-sold Interest Rate Hedging Products.
He also has experience of claims made against mortgage brokers and financial advisors for negligently recommending Interest Only mortgages.
Current and recent cases include:
Theo has experience in broker’s negligence claims – an area he is well placed to advise due to his practice in Insurance Law. His experience includes acting and advising on:
Theo has experience of claims involving a broad range of surveys (from regular residential property surveys to damp and asbestos surveys). His experience covers a spread of issues, from subsidence to damp, advice on value and the quantum of rectification works.
He is also experiences in claims against Property Managers, including:
Theo advises on multi-million pound claims against tax advisors, solicitors and accountants arising out of failed tax mitigation schemes, including employee benefit schemes and Enterprise Investment Scheme investments.
He has worked on these cases as sole counsel and as part of a wider team.
Current and recent cases include:
Theo specialises in sports-related commercial litigation and regulatory work.
He is recognised as a Leading Junior in Sports Law in Chambers & Partners and the Legal 500, in which he is described as “….a seasoned pro. A team player of fierce intellect.” and “….phenomenally bright and pays astounding attention to details. He is a very good team player and a skilful advocate.”
He has appeared for Liverpool Football Club in two of the largest football-related claims in the English courts and worked on disputes relating to the ownership of Sheffield United FC and Rangers FC. He acts on behalf of and against other Premier League football clubs and sporting institutions, advising on contractual issues between clubs and players, sponsorship disputes, negotiations with governing bodies, litigation with suppliers, and intellectual property issues.
He has also advised and acted on matters concerning Formula 1, golf, cricket, boxing, athletics and horse racing.
Featured sports cases:
In his advisory practice, Theo has provided assistance to several major sporting venues and institutions on the contractual problems caused by the Covid-19 pandemic, including advising:
Theo is a regular contributor to:
Theo has experience in insurance litigation, having acted for and against insurers in a number of sectors, including construction all risks insurance, professional indemnity insurance and legal expenses insurance.
Recently, he has advised and acted in a number of business interruption matters arising out of the Covid-19 pandemic.
He has acted in cases covering the full range of liability insurance, including legal expenses insurance, D&O, employers, public, product and professional indemnity. He has also appeared in a number of insurance fraud and misrepresentation matters, including the pursuit of fraudulent claimants.
He has experience in coverage disputes between insurers relating to run-off insurance and double insurance scenarios. He also has experience of highly complex multi insurer reinsurance disputes.
Ongoing insurance cases include:
Dubai Aerospace Enterprise (DAE) Ltd & Ors v Lloyd’s Insurance Company SA and Ors; Falcon 2019-1 Aircraft 3 Ltd v Lloyd’s Insurance Company SA and Ors;KDAC Aircraft Trading 2 Ltd v Chubb European Group SE and Ors (part of the wider ‘Russian Aircraft’ litigation): acting for insurers on consequential matters in this well-known and multi-faceted insurance litigation, which is, taken altogether, the biggest case the London market has seen for many years.
HDI Global Specialty v Legal Protection Group Limited & Ors: dispute concerning the management of books of ATE and BTE insurance by underwriting and claims handling agents, and return commissions.
X v Y (2025, ongoing): arbitrated coverage dispute under professional indemnity insurance for £10m+ legal defence costs, raising novel issues of the scope of cover for legal fees incurred by professionals.
Theo studied Modern History at Brasenose College, Oxford, where he was an academic exhibitioner. He then achieved a Distinction in the Graduate Diploma in Law at City University, London, placing second in his year group.
Theo has been awarded Hardwicke, Lord Haldane, Lord Denning, Lord Wolfson scholarships by Lincoln’s Inn. In 2017 the Inns of Court awarded Theo a Pegasus Scholarship to undertake a two-month fellowship in the United States to study comparative law.
Theo is a member of COMBAR, the British Association of Sport & Law, the PNBA and the Financial Services Law Association.
Outside of law, Theo’s first book, Fighters and Quitters: Great Political Resignations was published by Biteback in January 2018 (Hardback) and February 2019 (Paperback).
He wrote the chapter on George Canning in The Prime Ministers: Three Hundred Years of Political Leadership (Hodder & Stoughton, November 2020) and the chapter on Henry II in Kings & Queens (Hodder & Stoughton, September 2023).
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