Mark O’Neill
Team Leader
+44 (0)20 7842 3777
Click here to email
Call 2003
"She gives down-to-earth, accurate advice, and the clients adore her - she's a star of the future."
Legal 500
Mark O’Neill
Team Leader
+44 (0)20 7842 3777
Click here to email
Jamie Thomas
Team Leader's Assistant
+44 (0)20 3873 6851
Click here to email
Marianne Butler is an experienced commercial barrister, who has a core specialism in professional regulation and discipline.
Described in the directories as a “star”, “very approachable, good with the client and excellent on drafting documents”, she is held in the highest regard by clients. Marianne is the Chambers & Partners ‘Professional Discipline Junior of the Year’ 2022.
In addition to regularly acting for the regulators, Marianne has considerable expertise in undertaking highly discreet investigations and defence work for city firms and individuals in respect of complaints made against them, and in defending tribunal proceedings, alongside advising a wide range of firms with regards to ongoing regulatory / risk compliance in all regulatory fields. She is described in Legal 500 as being able to “rapidly analyse the best options in the circumstances where the course of action is very unclear”.
Whilst the nature of the work is by its nature typically highly confidential, Marianne is an experienced practitioner in the field and, as a result, is frequently invited to speak at regulatory conferences and to conduct training for professionals on all issues arising in this area.
As a skilled cross-examiner and advocate, Marianne prides herself on working tirelessly for her clients in handling what are often highly stressful cases requiring particularly sensitive attention and care.
SRA v Mishcon de Reya LLP & Ellen (Case No 12187-2021)
Instructed (with Richard Coleman KC) for a former partner of Mishcon de Reya LLP in successfully defending an allegation of misconduct relating to the alleged provision of banking facilities (for which Marianne was recognised by The Lawyer as ‘Barrister of the Week’).
SRA v Solicitor Z (Case No. 11941-2019)
Instructed (with Timothy Dutton, CBE KC) for Solicitor Z in proceedings brought in the SDT related to the compromise of employment claims in 1998. The proceedings were stayed on medical grounds in circumstances in which a fair trial of Solicitor Z was not possible.
#MeToo allegations
Instructed for a city firm in respect of the SRA’s investigation into a number of ‘#MeToo’ allegations (which resulted in the investigation being closed). Over the last few years Marianne has advised (and continues to advise) a significant number of firms and individuals on the handling of sexual misconduct allegations and related SRA investigations.
Alleged AML breaches
Instructed for a number of individual solicitors and firms in relation to concerns raised by the SRA in relation to AML/the provision of banking facilities.
SRA complaint
Instructed (with Greg Treverton-Jones KC) for a city firm in respect of a complaint made to the SRA arising out of a very substantial piece of Commercial Court group litigation (which resulted in the investigation being closed).
Advising and acting for major high street banks, private banks and other parties in relation to a wide variety of matters.
Acting with Jeff Chapman KC in proceedings against a major retail bank in respect of FX trading.
Acting with Ray Cox KC in proceedings against a major retail bank in respect of allegations relating to the suitability of financial products sold in 2008.
Acting with Richard Handyside KC on behalf of an international investment bank in relation to derivative transactions (including interest rate swaps) entered into between the bank and a foreign local authority involving a jurisdiction dispute.
Acting for a major retail bank in various proceedings brought against it regarding claims of ‘mis-sold’ interest rate swaps.
Acting with Mark Simpson KC for a private bank in proceedings for breach of contract and negligence in the TCC.
Acting for the Bank of Cyprus in a claim involving alleged undue influence.
Advising with Bankim Thanki KC with regard to the merits of a substantial breach of warranty claim.
Advising and acting for a variety of major high street banks concerning claims under mortgages with particular experience of issues of undue influence, mistake and rectification.
Advising and acting for a major high street bank in a case involving alleged false imprisonment.
Advising in connection with claims for compound interest in the light of the judgment in Sempra metals.
Advising and appearing for Barclays, HSBC and others in the County Court concerning issues arising out of the bank charges test case against the OFT.
Advising and acting for an individual against Barclays in successfully discharging and removing a legal charge of substantial value from the Charges Register on the grounds of limitation.
Advising and acting for Barclays Bank in numerous cases involving issues such as breach of mandate; the construction and enforceability of guarantees, loans and terms and conditions.
Advising the Consumer Action Group with regard to bringing claims against debt collectors and/or banks for harassment.
Acting for a lender in respect of a claim for breach of warranty of authority.
Marianne has experience of acting for both claimants and defendants in complex fraud disputes.
Acting on her own in complex UNCITRAL arbitration proceedings arising out of the construction of a facility for an African government.
Acting with James Lewis KC for the defendant company in a multi million pound dispute involving allegations of fraudulent misrepresentation.
Acting with Craig Orr KC in long-running and complex UNICTRAL arbitration proceedings arising out of the construction of a major strategic defence facility for an African government involving issues of alleged bribery and corruption.
Instructed for Barclays and Lloyds (as defendant and claimant) in numerous fraud claims in the High Court and County Court.
Acting with Adam Tolley KC for a claimant company in an 8 week trial in June 2011 involving allegations of conspiracy.
Acting with Craig Orr KC in ICC arbitration proceedings arising out of the construction and supply of a naval vessel to African state government involving alleged fraud.
Acting with Michael Crane KC for insurers in respect of a claim arising out of the August 2011 riots under the Riot (Damages) Act 1886. See [2014] 3 WLR 576 (Court of Appeal) and [2014] 1 ALL ER 422 (Flaux J).
Acting with Patricia Robertson KC for a large firm of financial advisors (the lead defendant of 500 defendants) in respect of proceedings brought by the FSCS in the Commercial Court arising out of the collapse of Keydata.
Acting with Richard Handyside KC on behalf of an international investment bank in relation to a number of derivative transactions (including interest rate swaps) entered into between the bank and various foreign local authorities involving jurisdiction disputes.
Acting for a major retail bank in various proceedings brought against it regarding claims of ‘mis-sold’ interest rate swaps.
Acting with Finola O’Farrell KC in a multi-million pound contractual dispute concerning the biggest transport advertising contract in the world.
Acting with Adam Tolley KC for a financial advisory business in proceedings brought by the company against individuals and a competitor business for breach of restrictive covenants, conspiracy and breach of confidence, involving an eight-week trial in the QBD [2012] EWHC 224.
Acting with James Lewis KC for the defendant company (the holding company of a substantial multinational enterprise) in a dispute involving allegations of fraudulent misrepresentation.
Acting with Mark Simpson KC for a private bank in proceedings before the TCC.
Bezant v Rausing and others [2007] EWHC 1118)
Dealing with claims by vexatious litigants (including a successful application for an extended civil restraint order.
Acting for a large telecommunications company in respect of a multi-million pound third party debt order.
Instructed with Anthony Boswood QC by a high-profile individual to strike out a substantial claim against him for want of prosecution.
Acting for an individual in setting aside a substantial two-year old judgment obtained against him by the Inland Revenue.
Acting and advising in a full range of general commercial disputes. Recent subject matter has included share purchase agreements, issues arising under the Commercial Agents Regulations and in respect of claims against builders and other construction contractors.
Advising an educational establishment with regard to recovery of unpaid funding from the European Regional Development Fund.
Instructed on an application for detailed assessment pursuant to section 70(4) of the Solicitor’s Act 1974.
Acting on her own in complex UNCITRAL arbitration proceedings arising out of the construction of a facility for an African government.
Acting with Jeff Chapman KC in the Commercial Court and related arbitral proceedings arising out of an oil exploration dispute off Sierra Leone.
Acting with Andrew Mitchell KC and Derrick Dale KC in the Commercial Court and related arbitral proceedings in respect of a dispute about the operation of an African copper mine. See the decision of Blair J in [2013] 1 C.L.C. 456.
Acting with Craig Orr KC in long-running and complex UNICTRAL arbitration proceedings arising out of the construction of a major strategic defence facility for an African government involving allegations of bribery and corruption.
Acting with Craig Orr KC in ICC arbitration proceedings arising out of the construction and supply of a naval vessel to African state government.
Marianne was named Professional Discipline Junior of the Year at the Chambers & Partners 2022 Bar Awards, and was shortlisted as Professional Disciplinary & Regulatory Junior of the Year by The Legal 500 at its 2023 Bar Awards. She is also ranked by both Chambers & Partners and The Legal 500 (the latter in the top tier) for Professional Discipline. Clients comment that she is “an effective advocate who commands the confidence of the tribunal.”
SRA v Carr, Benson, Brown, Gibson, Green & Webb (Case No 11608-2017)
Instructed (with Tim Dutton KC) for a number of senior individuals in respect of proceedings brought in the SDT regarding the collapse of the Manchester law firm, Cobbetts.
Ted Baker audits
Instructed for the Financial Reporting Council (leading Max Evans), in respect of its investigation into the conduct of KPMG and the audit partner concerning Ted Baker audits, concerning the provision of expert witness services by the auditor in a commercial court claim, threatening independence.
Instructed for the FRC (leading various juniors including Max Evans and Nicolas Damnjanovic) in a number of investigations into city auditors and accountants.
Instructed by a magic circle firm (with Patricia Robertson KC) in respect of the SRA’s investigation into sexual misconduct allegations.
Instructed for a number of partners at city firms in respect of allegations of misconduct relating to claiming expenses.
Instructed (with Tim Dutton KC) for the senior partner at a city firm in respect of complaints arising out of a substantial piece of Commercial Court litigation.
Acting for a large number of city firms (and individuals) in respect of complaints made to the regulator about the conduct of the firm and senior individuals within it (ongoing).
Advising various city firms as to matters of regulatory compliance (such as document ownership and destruction, confidentiality, conflicts of interest/privilege, whether they were required to make a report of serious misconduct etc) (ongoing).
R (on the application of AM) v DPP [2012] EWHC 2381 (Admin)
Acting with Tim Dutton KC for the Solicitors Regulation Authority in the landmark cases brought by two men suffering from locked-in syndrome who wanted to be assisted to die.
Instructed by the Law Society/SRA in relation to appeals to the Master of the Rolls under the Solicitors Act 1974: see e.g. Re a Solicitor No. 18 of 2008 [2008] EWCA Civ 1358. Instructed in another appeal with Nigel Giffin KC.
Advising the Law Society/SRA with regard to the construction of the Solicitors’ Indemnity Insurance Rules 2005 (advising as to, inter alia, the liability of salaried partners and regarding issues concerning successor practices).
Instructed by a mortgagee in a substantial claim against solicitors for breach of warranty of authority and negligence.
Acting in proceedings brought pursuant to s. 70 of the Solicitor’s Act 1974.
Acting with Patricia Robertson KC for a large firm of financial advisors (the lead defendants of 500 defendants) in respect of proceedings brought by the FSCS in the Commercial Court arising out of the collapse of Keydata.
Mason v Mills & Reeve [2011] 1 W.L.R. 2735 (CA), [2011] EWHC 410 (ChD), 2012] 4 Costs L.O. 511
Acting with Mark Simpson KC for Mills & Reeve solicitors (in the now the leading case on late amendments), at the trial of the action and on appeal (solicitors’ duty of care – management buyout – IHT and CGT advice).
Acting with Mark Simpson KC for a private bank in proceedings for breach of contract and negligence in the TCC.
Bezant v Rausing & Others [2007] EWHC 1118 (QB)
Acting for the same liquidator in successfully striking out a subsequent multi-million pound claim against him in negligence.
Bezant v Cork [2006] All ER (D)
Acting for a liquidator in successfully striking out multi-million pound proceedings brought pursuant to s. 212 of the Insolvency Act 1986.
Instructed as junior with Michael Green by the Treasury Solicitors in a substantial trial concerning proceedings brought pursuant to s. 8 of the Company Directors Disqualification Act 1986.
Acting in a number of other cases involving issues of alleged negligence against professionals across a wide range of disciplines.
Mark O’Neill
Team Leader
+44 (0)20 7842 3777
Click here to email
Jamie Thomas
Team Leader's Assistant
+44 (0)20 3873 6851
Click here to email