Sinead O’Callaghan is an experienced litigator with a wide-ranging practice who, sources in Chambers & Partners describe as “an outstanding practitioner”, “extremely helpful, responsive and conscientious” and “very personable and a good lawyer”.   Sources in Legal 500 state that she is “consistently excellent” and a “real fighter”.

Sinead has a broad range of domestic and international litigation and arbitration experience with particular strengths in banking and finance, civil fraud, contentious trust and succession disputes, IT/telecoms disputes and professional negligence matters.

Sinead’s banking and finance experience includes acting for receivers appointed over a structured investment vehicle in respect of disputes with the vehicle’s bankers and noteholders.  She has also advised PLCs, federal states and high-net-worth individuals on claims arising from the mis-selling of complex financial products.

Her civil fraud experience includes cases involving cyberfraud, unlawful means conspiracy, fraudulent misappropriation of assets, and multi jurisdictional asset tracing exercises.

Her IT/telecoms experience includes acting for clients including global telecoms and IT companies in outsourcing disputes, contractual interpretation claims, and technical claims involving issues such as web scraping and industry defamation.

Her professional negligence experience includes both acting for claimants and defending disciplinary investigations and/or prosecutions brought against professional services organisations by various professional bodies, including the Institute of Actuaries, the FRC and the Institute of Chartered Accountants.

She has also advised on company/corporate disputes including partnership, joint venture and shareholder disputes.


Sinead obtained a BSc from Bristol University in Biological Sciences (specialising in Genetics) and was awarded distinctions in both the Common Practice Examination and Legal Practice Course, which she studied at the College of Law in London.

Sinead trained with Theodore Goddard (subsequently renamed Addleshaw Goddard after a merger), qualifying as a solicitor in March 2003. Sinead worked for Addleshaw Goddard for four years following her qualification and then moved to Mayer Brown International, where she worked for three years as a senior associate before leaving that firm to join Cooke, Young & Keidan in January 2010.

What the legal directories say

Sinead has been consistently ranked as a leading lawyer in the Chambers and Partners and Legal 500 Guides for banking litigation and commercial litigation. Former editions of Chambers have said that sources describe her as “very focused and intelligent,” adding: “She doesn’t get flustered and she’s a good strategist” and “She is an experienced litigator who always has her finger on the pulse of the case and where it’s going”.  Former editions of the Legal 500 Guide have stated that she is a “skilled litigator”, “calm and knowledgeable” and that she “motivates the troops with a combination of hard work and good humour”.

Sinead is also recommended as a global leader in commercial litigation by Who’s Who Legal (WWL).

Professional groups

Sinead is a member of the Law Society of England and Wales, various fraud forums, and the International Bar Association.

Cases of Note

  • Topalsson GmbH v Rolls-Royce Motor Cars Ltd  [2023] EWHC 1765 (TCC): acting for a German software development company against the luxury car manufacturer Rolls-Royce in relation to a software project to deliver a real-time configurator for the Rolls-Royce Ghost.

  • Morina and Others v Scherbakova and Others (Re Estate of Vladimir Alekseyevich Scherbakov) [2022]: acting for beneficiaries in complex high value international probate litigation with proceedings in England, Belgium and various other jurisdictions.

  • Representing an Additional Party in arbitration proceedings seeking interpleader relief in respect of contractual commission payments brought under the LCIA rules.

  • Representing shareholders in a joint venture dispute concerning an Angolan oil project governed by the UNCITRAL arbitration rules.

  • Aries GNH (Operations) Ltd v Robson Asset Management Manco Ltd [2020]: successfully defending a winding up petition brought off the back of a complex structured finance transaction involving a number of cross-collateralising and cross-defaulting loans.

  • A and B  -v- C, D and E [2020] EWCA Civ 409 and [2020] EWHC 258 (Comm): acting for the successful appellants in the Court of Appeal and Commercial Court in an application under s. 44 Arbitration Act 1996 to compel the evidence of a non-party witness in aid of a New York arbitration.

  • Representing a major African parastatal in relation to a $500m+ dispute brought under the UNCITRAL arbitration rules before a distinguished three-member tribunal [2020].

  • Re Infund LLP: [2018] EWHC 1306 (Ch); [2019] EWCA Civ 1673: Proceedings ancillary to a US$2billion share dispute in Mexico. The English Court (to the Court of Appeal) considered for the first time the meaning of certain statutory provisions applying to both companies and LLPs in the context of an administrative restoration. The Court determined that it had the power to reverse the restoration of an LLP in certain circumstances.

  • CMOC Sales & Marketing Ltd v Persons Unknown & 30 others [2018] EWHC 2230 (Comm): acting for international commodities business subject to a sophisticated Business Email Compromise fraud. Obtained first-known reported worldwide freezing injunction against ‘Persons Unknown’.

  • Mazarona Properties Ltd v Financial Ombudsman Service [2017]: This case concerned the ability of the FCA to police the review process that it set up with various banks in relation to the sale of interest rate hedging products.

  • O’Hare & Anor v Coutts & Co [2016]:  This case centred on the alleged mis-selling of investment products to the O’Hares by their former financial advisors, Coutts & Co. The case was of particular interest for the way that it examined the scope of the duty of care in negligence owed by financial advisors.

  • Confidential ICC Emergency Arbitration Proceedings [2012]: In December 2012, Sinead was involved in successfully defending emergency arbitrator proceedings in the energy sector under the ICC rules. This was the first set of proceedings of this kind following the introduction of the ICC emergency arbitrator rules in January 2012. The emergency arbitration proceedings were followed by substantive ICC arbitration proceedings.

  • RBS v Highland Financial Partners LP & Ors [2010] and [2012]: A widely reported banking litigation case relating to a €500 million CDO issue of securities and the subsequent liquidation/valuation of the portfolio following the Autumn 2008 financial crash. The bank was subjected to strong judicial criticism for conducting a “sham” auction of leveraged loans and was found to have lied to and deceived its counterparty. On the back of the 2010 Judgment, in early 2011 Highland commenced proceedings in Texas against RBS for, inter alia, fraud, seeking damages of at least $100 million. This step prompted RBS to seek and obtain an interim anti suit injunction from the English Commercial Court which was rejected as a result of Highland’s successful arguments.

  • North Shore Ventures Limited v Anstead Holdings Inc & Ors [2010] (First Instance) and [2011] (Court of Appeal): Defending a very high value claim brought in the Commercial Court by a company whose shares were owned by the Russian oligarch Boris Berezovsky. The case considered the extent to which a lender is under a duty to disclose unusual facts to a prospective guarantor and whether the failure to do so renders a guarantee void.

  • Sinead acted on a pro bono basis for Justice, a leading civil liberties organisation, in respect of its intervention in the House of Lords appeal in R (on the application of Corner House Research and others) v Director of the Serious Fraud Office [2008]. This was a judicial review of the decision of the Serious Fraud Office to halt investigations into alleged bribery on the part of BAE Systems Plc in respect of a Saudi arms deal.