“Sinead O’Callaghan is a partner and an experienced litigator with a wide-ranging practice who, sources describe as “very focused and intelligent,” adding: “she doesn’t get flustered and she’s a good strategist (Chambers & Partners)”

Sinead has a broad range of domestic and international litigation and arbitration experience with particular strengths in banking and finance, civil fraud, contentious trust 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 ranked as a leading lawyer in the Chambers and Partners Guide and Legal 500 Guide for banking litigation and commercial litigation. The current edition of Chambers says that sources describe her as “very focused and intelligent,” adding: “She doesn’t get flustered and she’s a good strategist”.  Former editions have commented that “She is an experienced litigator who always has her finger on the pulse of the case and where it’s going”, that she is “very astute” and “very tenacious and also very driven” and that she has earned praise from clients for “strong commercial acumen and useful, practical advice”. The current edition of the Legal 500 Guide also states that she is a “skilled litigator”, “calm and knowledgeable” and that she “motivates the troops with a combination of hard work and good humour”.

Professional groups

Sinead is a member of the Law Society of England and Wales, various fraud forums, and the Irish International Business Network.

Cases of Note

  • 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.

  • Re Infund LLP: [2018] EWHC 1306 (Ch); [2019] EWCA Civ 1673 – Proceedings ancillary to a US$2billion share dispute in Mexico. The English Court 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.

  • Sinead also 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.

  • 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].

  • Confidential [2014 – 2019]. Sinead was involved in defending a Norwich Pharmacal application made in support of high value and high profile proceedings in Mexico which involve allegations of fraud. There were related ongoing proceedings in the Companies Court in which the Court examined the allegations made in the Mexican proceedings.  The Companies Court judgment is subject to an appeal to the Court of Appeal which will be heard in Summer 2019.

  • 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 are owned by the well-known 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.