"technically brilliant and genuinely cares about getting the right result."  "If I was being sued, it would certainly be Sean who I'd want representing me."
Chambers UK 2018


Sean Connolly is a partner in the Insurance & Reinsurance practice of the London office. He advises clients who are involved in high value professional liability or financial institutions disputes. He also has considerable experience in handling complex insurance and reinsurance market disputes across a wide range of product sectors.

Sean has extensive experience in handling professional liability disputes in areas including law firm liability, accountancy, chartered surveying, investment banking, property management, insurance and reinsurance brokers and design consultancies. He has also handled matters involving investment banks, offshore investment companies, trust companies, stockbrokers and other financial institutions. He has also represented major domestic and overseas insurance and reinsurance companies, Lloyd’s syndicates and their representatives, insurance brokers and other intermediaries.

Sean also has particular experience in coordinating multi-jurisdictional litigation and insurance investigations. He has also acted in a wide range of cases for both insurers and reinsurers on claims involving motor manufacturers, the iron and steel industry, electrical products, heavy plant engineering, paints, pharmaceuticals and health products.

Sean has served in a number of global management positions at Mayer Brown for the past 15 years and was Senior Partner of Mayer Brown International LLP between 2007-2017. He was a founding partner of the firm's Insurance Group and a Practice Leader in the firm's global Litigation Practice.

Spoken Languages

  • English


  • Defending a number of leading international law firms and their insurers in a series of large commercial disputes.
  • Representing insurers on a major brokers Errors & Omissions programme.
  • Representing a major investment house and its insurers in defence of claims arising from a series of emerging markets investments.
  • Representing London market reinsurers in an arbitration concerning a large South American bank.
  • Advising insurers on claims portfolio matters following the financial collapse of a major commercial property adviser.
  • Acting for London market insurers concerning the collapse of a number of Icelandic banks.


Queen Mary, University of London, Bachelor of Laws


  • England and Wales

Consistently ranked as a leading individual:

  • Listed as a Senior Statesman. He is a deeply experienced practitioner, sources say: "He is a very bright lawyer and a very well-known practitioner." (Professional Negligence)
    "Extremely able insurance lawyer" Sean Connolly demonstrates experience handling a range of insurance disputes, particularly those involving financial lines and professional liability. Interviewees highlight his "high-quality work and good judgement." (Insurance)(Chambers UK 2019)
  • Sean Connolly is highly experienced in handling sophisticated insurance and reinsurance disputes. His areas of expertise include professional liability claims and matters relating to financial institutions. He also provides a range of non-contentious advice concerning risk assessment and loss prevention. (Insurance)
    Sean Connolly is "technically brilliant and genuinely cares about getting the right result." Connolly focuses on advising insurers and law firms. He is very highly regarded, as demonstrated by one source, who comments: "If I was being sued, it would certainly be Sean who I'd want representing me." (Professional Negligence) (Chambers UK 2018);
  • Sean Connolly is "an exceptional lawyer" and is particularly noted for his expertise in disputes in the financial sector. (Legal 500 2017);
  • The "very good" Sean Connolly frequently handles sophisticated negligence disputes, many of which involve an offshore or international element. He advises insurers on cases that relate to major trust companies and financial institutions, providing expert knowledge on the duties of company directors, fiduciaries and trustees. (Chambers UK 2017);
  • According to reporters, he "is hands-on, smart and a very good tactician." (Chambers UK 2016);
  • Chambers UK 2016 ranks 30 Mayer Brown practices and 47 lawyers - Sean is ranked as a Star Individual for professional negligence.
  • Ranked as a Leading Individual, Sean Connolly is "very experienced". (Legal 500 2015); 
  • Sean Connolly is a "very pragmatic" and well-regarded insurance and reinsurance solicitor, with particular expertise in financial institution and professional liability risk. "If I was being sued, he is the guy that I would want representing me," said one prominent peer.  He is also described as "very commercial, with a great depth of technical knowledge." He is noted for his expertise in legal professional negligence. Sources say: "He is very calm, phenomenally bright, measured and sensible - you know you get the advice and service from him."  (Chambers UK 2015);
  • "truly brilliant" (Legal 500 2014);
  • is described by sources as being "extremely strong" and an "excellent practitioner". Connolly is known as "a highly effective operator" and is sought by major insurers for his expertise (Chambers UK 2014);
  • is "truly exceptional" (Legal 500 2013);
  • is ranked as a star individual, and held in high esteem as an outstanding strategist. Sources "would recommend him to anyone with a high-value, complex case" on their hands. His calm demeanour and legal talent make him a real standout practitioner. He is a "brilliant all-round lawyer" (Chambers UK 2013);
  • is a "real class act who always goes the extra mile for his clients" (Chambers UK 2012);
  • is "outstanding" (Legal 500 2012);
  • is "excellent" (Legal 500 2011);
  • is the "first choice for complicated and unusual cases" (Chambers UK 2010);
  • is "one of the very best" and commended for his "far-reaching strategic vision" (Chambers & Partners UK Directory 2009);
  • has been lauded for his "seriously high quality” work and has been described as a lawyer who “has one of the best reputations in the market” (Legal 500 UK 2006/2005).