Perry Brown
    Perry Brown
    Senior Practice Manager
    +44 (0)20 7419 6206
    Tommie Drury
    Tommie Drury
    Practice Manager
    +44 (0)20 7419 6203
    Matthew Evans
    Matthew Evans
    Assistant Practice Manager
    +44 (0)20 7691 2424
    Contact the Practice Managers

    Overview: Oliver Assersohn – “a truly excellent barrister” (Legal 500) – specialises in commercial matters and particularly in financial services, including regulation, for which he has been ranked by the foremost independent legal directories for many years.

    Commercial/ Chancery litigation: A “financial services and banking specialist who has a wealth of expertise in the area”  with “… a broad chancery and commercial practice…He is incredibly diligent and hard-working, and continues to impress with his technical knowledge.” (Chambers & Partners). Also ranked by Legal 500 in commercial litigation, financial services and in the separate category of banking and finance and described as ‘Highly personable and a dream to work with – slots into the team very well and a tremendous team player.’

    Recent work includes:

    • Acting on behalf of purchasers of an IFA business suing the sellers for breach of warranty (ongoing). Successfully argued at a trial of a preliminary issue that various breaches of warranty were wilfully concealed and so the claim could proceed (Liberty Partnership Ltd v Tancred &Anr [2018] EWHC 2707 (Comm);
    • Successfully argued on behalf of a liquidator of a money-lending business that the assignment of the loan book should be set aside (Barons Finance Ltd v Barons Bridging Finance 1 Ltd & Ors [2018] EWHC 496 (Ch) (appeal dismissed by the Court of Appeal [2019] EWCA Civ 2074);
    • Acted for a number of years for the second largest organisation in Ethiopia which successfully defeated a US$30m claim on grounds of forum non conveniens (Court of Appeal judgment, Mengiste v EFFORT & Ors [2017] EWCA Civ 1326).

    Financial services regulation: Previous accolades in the directories include: a “highly regarded junior”; an effective advocate”; and, someone who provides “excellent” written work and “clear and practical advice”. 

    • Oliver was seconded to the Regulatory Decisions Committee of the FSA (now FCA) therefore providing him with a valuable insight into how contested enforcement actions are approached;
    • He has acted in a number of the leading cases including, acting for a brokerage in the first ever case to challenge the FCA’s assessment of penalty following a focused resolution agreement (FCA v Linear Investments [2019] UKUT 0115 (TCC)) and advising in a number of high-profile investigations against both individuals and firms (example matters are set in the “areas of experience” section);
    • He is the editor of the Decision Procedure and Penalties Manual Commentary in Butterworths Financial Regulation Service.

    Arbitration and international law: Oliver is a member of the Swiss Arbitration Association and Associate Member of the Chartered Institute of Arbitrators and his recent work includes:

    • Acting on behalf of an African State defending a US$300,000,000 claim for alleged breaches of a bilateral investment treaty concerning a construction project. Case involved cross-examination of a number of witnesses as to fact and liability including in respect of the claimant’s DCF analysis;
    • Numerous cases for states in respect of a number of litigation issues including claims involving questions of state immunity (e.g. instructed at first instance and for the first appeal in the leading case of Jana v Libya);
    • An alleged breach of a commercial arbitration agreement by solicitors acting for one party reporting the matter to their regulator.

    Further information: Please see sections below for examples of Oliver’s work. If any further information is required please do not hesitate to contact one of Oliver’s clerks or, if an existing client, to telephone Oliver direct in Chambers or on his mobile.

    Areas of experience

    Checked sections will be included in the PDF download.

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    • Arbitration

      Two ongoing cases that Oliver is working on are cited below by way of example:

      A Construction Company v an African State

      Instructed initially as sole counsel and subsequently leading Tom Stewart Coats on behalf of an African State defending a US$300,000,000 claim for alleged breaches of a bilateral investment treaty.

      Dispute arising from settlement

      Instructed on behalf of a financial services firm facing allegations of a breach of a settlement agreement.

    • Aviation

      On Tuesday 30 April, Oliver joined other speakers from XXIV in hosting a seminar on the grounding of Boeing’s 737 Max aircraft which explored:

      • The problem with the Max 8 and 9 explained
      • The impact on sale purchase and finance agreements – full / partial frustration
      • The effect on operating and finance leases, on which Oliver spoke with Edward Cumming QC
      • Damages for grounded aircraft – direct and indirect losses


      Provided assistance to leading airline in respect of inaccurate media reports about performance.

    • Banking and Financial Services

      Financial Services

      A core area of Oliver’s practice several examples of regulatory cases are provided below [for banking cases please see following section]:

      FCA v Linear Investments, Upper Tribunal (6 March 2019): Acted for a brokerage before the Regulatory Decisions Committee and then before the Upper Tribunal in the first ever case to be referred to the Upper Tribunal in which a firm had agreed a focused resolution agreement but disputed the FCA’s proposed level of penalty.

      Zai Corporate Finance Limited v (1) The AIM Disciplinary Committee (2) London Stock Exchange [2017] EWCA Civ 1294: Acted as sole counsel on behalf of Zai Corporate Finance Limited, a nomad facing disciplinary proceedings brought by the ADC judicially reviewing a decision of the AIM Disciplinary Committee.

      FCA v W

      Acting for brokerage and CEO subject to FCA investigation in respect of alleged part in an alleged fraud of several hundred million pounds.

      X v FCA

      Acted for individual subject to FCA enforcement investigation and alleged to have participated in large scale and serious conspiracy.

      Y v FCA

      Recently acted for individual applying to lift a prohibition order on an individual.

      Z v A Bank

      Advising compliance officer of a major global financial institution in respect of her whistleblowing and subseqient disciplinary proceedings in context of wider regulatory investigation.

      A company seeking investment: Advised a company that had developed a cutting edge technology whether or not their prospectus to investors and which had been used to raise several million pounds was misleading and in breach of ss. 89 and 90 of the Financial Services Act 2012


      After secondment to the Regulatory Decisions Committee of the FSA, continued to advise the Committee in a variety of cases. For example, he advised the Committee in FSA v (1) Visser (2) Fagbulu in which a ban and £2.1m fine were imposed on a hedge fund chief executive and chief financial officer for deceiving investors and market abuse.


      A lender v X 

      Acted for a lender bringing proceedings against a borrower in relation to a £4m mortgage. The borrower was seeking to avoid liability by (among other things) arguing that the loan was made in breach of the Financial Services and Markets Act (2000) and is therefore unenforceable. Settled during opening speeches.

      Interest rate swap mis-selling claims

      Acted in a large number of interest rate swap mis-selling claims against banks. Represented individuals and companies in pursuing compensation through the courts and advising on aspects of the FCA ordered redress scheme. In addition to the familiar contractual, common-law and statutory causes of action he has been involved in cases alleging negligence in relation to the implementation of the FCA Redress Scheme.

      Y Ltd v A Bank

      Acted for a company seeking to bring Holmcroft style judicial review proceedings of the actions of an independent reviewer.

      Z and the LIBOR investigation

      Instructed on behalf of a party that has been investigated in relation to the investigation into the manipulation of LIBOR in the context of potential civil claims.


    • Commercial Litigation

      Oliver is instructed in a number of ongoing matters in the High Court and recent examples of past work are cited below.

      Barons Finance Ltd v Barons Bridging Finance 1 Ltd & Ors, Court of Appeal [2018] EWHC 496 (Ch)

      Acting for joint liquidator in respect of a declaration an assignment was void under s. 127 of the Insolvency Act 1986 (“IA”) and that it should be set aside under s. 238 and s. 423 of the IA.

      Mengiste & Anr v EFFORT & Ors [2017] EWCA Civ 1326: Acted on behalf of defendants facing a $30m claim who successfully disputed jurisdiction grounds of forum non conveniens.

      X v Brokerage House (settled after pleadings and mediation)

      Recently acted for claimant in High Court claim alleging breach of contract, negligence and the FCA rules in relation to the brokerage house’s decision to (among other things) follow the instructions of a person to whom the claimant had granted third party authority and which resulted in the loss of almost the entire sum invested.

      Y v Z 

      Claim by major financial institution against another in respect of unpaid commission payments which the defendant refused to pay on the basis that to do so would breach the FCA Rules (they had not been disclosed by the defendant to its customers).

      Mengiste & Anor v Endowment Fund for the Rehabilitation of Tigray & Ors [2014] EWHC 4196 (Ch)

      Following the decision referred to above and the claimant’s subsequent application in Ethiopia, represented the defendants as sole counsel in successfully resisting the claimants’ application to lift the stay in this US$20m claim. The claimants currently have permission to appeal following an oral hearing before the Court of Appeal on condition they pay the defendants £200,000 in costs.

      Mengiste & Anr v EFFORT & Ors [2013] EWHC 1718

      Acted for the defendants who were being sued for $20m by the claimants who allege that the defendants obtained a judgment in Ethiopia by fraud. The defendants applied to stay the claim on the grounds of forum non-conveniens and the central issue has been whether or not there is cogent evidence that the claimants will not receive justice in Ethiopia. The claim was stayed on grounds of forum non-conveniens pending the Claimants being allowed time to make an application in Ethiopia. The case involved a range of subsidiary issues, most notably whether an expert witness in fear of his life could remain anonymous ([2012] EWHC 2782 (Ch)). Other reported decisions as part of the EFFORT litigation included: [2013] EWHC 598 (Ch) (22 March 2013); [2013] EWHC 856 (Ch) (25 March 2013); EWHC 857 (Ch) (26 March 2013); EWHC 1087 (Ch) (1 May 2013); EWHC 1003 (Ch) (14 August 2014).

      EFFORT & Ors v Rylatt Chubb [2013] EWHC 1003

      Acted for EFFORT in an application for wasted costs against the claimants’ solicitors relating to their choice of expert for the underlying action. The matter was appealed to the Court of Appeal.

      The Great Estates Group Limited v Digby [2011] EWCA Civ 1120, [2011] 43 EG 104(CS)

      Acted for the vendor of a private home who was sued by an estate agent who claimed that he was instructed as a sole agent and that he was entitled to damages for loss of the chance of earning commission when the sale of the property was not arranged through him. Successfully argued at first instance that the contract could not be enforced because the agreement did not comply with the Estate Agents Act (1979). The claimant appealed to the Court of Appeal, who by a majority (Lord Justice Lloyd dissenting) upheld the first instance decision. One of several estate agency cases undertaken.

    • Hedge Funds & Structured Investment Vehicles

      Oliver’s grounding in financial services regulation and commercial litigation makes him well placed to handle disputes in respect of hedge funds and structured investment vehicles.

      Oliver has advised a number of investment vehicles in recent years and was previously instructed by the Regulatory Decisions Committee of the FSA in FSA v Mercurius Capital Management, FSA v Visser and FSA v Fagbulu. The case involved a number of important issues and resulted in what was at the time the biggest fine imposed on an individual for market abuse.

    • Insolvency

      Barons Finance Ltd v Barons Bridging Finance 1 Ltd & Ors, Court of Appeal [2018] EWHC 496 (Ch)

      Acting for joint liquidator in respect of a declaration an assignment was void under s. 127 of the Insolvency Act 1986 (“IA”) and that it should be set aside under s. 238 and s. 423 of the IA.

      X v Y (Chancery Division, August 2017)

      Acted for trustee in bankruptcy in obtaining an urgent freezing injunction before Mr. Justice Mann and instructed in the substantive underlying claim for breaches of the IA 1986.

      X v Z (2016)

      Instructed on behalf of financial institution in bankruptcy proceedings against a debtor.

    Other information

    • Recommendations

      “He’s technical but also sensitive to business and commercial implications – he weighs in in a way that furthers business goals.” “An ambitious and skilled advocate.” Financial Services, Chambers & Partners 2022

      “Oliver takes ownership of a case from the outset and will work tirelessly in support of the client’s case. He is very bright, and has significant FCA expertise.” Financial Services Regulation, Legal 500 2022

      “A superbly able junior, if there is an answer to a problem he will find it.” Banking & Finance, Legal 500 2022

      “Oliver has a rare mix of commercial acumen, empathy and wide-ranging communication skills which enable productive engagement at all levels.” Commercial Litigation, Legal 500 2022

      “An impressive specialist in FCA enforcement-related matters.” “He’s very responsive, very easy to deal with and the quality of his advice is also very good.” Financial Services, Chambers & Partners 2021

      “Highly personable and a dream to work with – slots into the team very well and a tremendous team player.” Banking & Finance, Legal 500 2021

      “Technically outstanding, and very hard working and responsive – he also has very sound client management (expectation management and empathy) skills.” Commercial Litigation, Legal 500 2021

      “Excellent attention to detail, good analytical skills coupled with regulatory knowledge and experience.” Financial Services, Legal 500 2021

      “He is easy to get along with and thorough in his advocacy, and pitches his arguments in a respectful way to the tribunal.” Oliver is “very accessible, very user-friendly and works really well as part of the team.” Financial Services, Chambers & Partners 2020

      “Very responsive and hardworking, his input is always measured and valuable”. Banking and Finance, Legal 500 2020

      Bright, well informed and has good judgement”. Financial Services, Legal 500 2020

      “A highly regarded junior who is an expert at handling complex issues relating to mis-sold investments and breaches of the perimeter. Having been on secondment to the FCA, he has highly valuable insight into the workings of the regulator….”Approachable, helpful and diligent.” “A credible and hard-working advocate.” Financial Services, Chambers & Partners 2019

      “Very good for fraud and financial regulatory investigations.” Financial Services, Legal 500 

      “Highly rated for banking and financial services disputes.” Banking and Finance, Legal 500

       “His written work is always excellent, he provides clear and practical advice and he deals with clients in a very empathetic manner.” Financial Services, Chambers & Partners 2017

      “Technically bright, hardworking, a team player and approachable.” Business and Regulatory Crime, Legal 500 2016

      “A truly excellent barrister, who knows the ins and outs of FCA regulations.” Banking and Finance, Legal 500 2016

      “A financial services and banking specialist who has a wealth of expertise in the area. He has a broad chancery and commercial practice…He is incredibly diligent and hard-working, and continues to impress with his technical knowledge.” Chambers & Partners 2016

      “He has a very innate feel for the regulators’ expectations and is very good at the detail. He understands the issues and is very diligent and analytical.” Chambers & Partners 2016

      “Very bright, exceptionally hardworking, personable and very practical. He really understands the FCA’s enforcement process.” Chambers & Partners 2015

      “He is calm, knowledgeable, diligent and keen to assist. A pleasure to work with.” Chambers & Partners 2015

      “Extremely well regarded for financial services and FCA regulatory issues.” “The barrister to go to with challenging issues.” Legal 500 2015

       “An absolute delight to work with.” Chambers & Partners 2014

       “Highly experienced in regulatory and FCA related matters.” Legal 500 2014

      “A financial services specialist.” Legal 500 2014

      “First rate.” Chambers & Partners 2013

      “An enviable reputation as a leading junior in financial services law.” Chambers & Partners 2012

      “The ‘knowledgeable, calm and authoritative’ Oliver Assersohn is recommended for contentious financial services work, where ‘his experience is almost unique’.” Legal 500 2012

      “Highly diligent.” Chambers & Partners 2011

      “Invaluable knowledge of the FSA disciplinary process.” Legal 500 2011

      “Understands how the regulator lives and breathes.” Chambers & Partners 2010

    • Publications
      • Articles in numerous publications on financial services and banking matters (e.g. JIBFL November 2015 (the proposed EU Banking Union), JIBFL July/ August 2017 (Financial services law as a sword: cutting down contracts).
      • Co-author the chapter of COMBAR’s paper on Brexit (January 2017) entitled “MiFID, MiFID II and MiFIR: (1) Passporting and Equivalence Regimes; (2) Brexit effect on UK financial services dispute resolution” (December 2016).
      • Editor of the Decision Procedure and Penalties Manual Commentary in Butterworths Financial Regulation Service (c. 40,000 words) (published March 2015).
    • Lectures and seminars

      Oliver is regularly invited to give talks to solicitors firm and take part in panel discussions (for further details please contact Oliver’s practice management team by email to

    • Appointments & Memberships
      • Member of FSLA (founding member)
      • COMBAR
      • Associate member of Chartered Institute of Arbitrators.
      • Advocacy trainer for Middle Temple.
    • Awards
      • Queen Mother Fund Scholarship (2002)
      • Blackstone Entrance Exhibition (2002)
      • Queen Mother Fund Scholarship (2001)