Aaron acts for clients in relation to coverage of insured losses in diverse sectors including financial services, hospitality and retail, manufacturing, logistics, sports and entertainment. He is experienced in all commercial lines of business, including business interruption, directors and officers, professional liability, cyber, environmental risks, property and casualty. Aaron spent eight years practising in the Asia Pacific region (Singapore, Hong Kong, Bangkok), and is particularly experienced at resolving international and cross-border claims, often via arbitration.

In recent times, Aaron has established himself as a leading policyholder advocate in the field of Covid-19 business interruption coverage, and in both 2022 and 2023 Aaron’s cases were selected by The Lawyer as the only insurance cases to feature in the publication’s annual Top 20 Cases list. In June 2023 he was named by The Times as Lawyer of the Week in recognition of the successful verdict in London International Exhibition Centre v RSA & Ors [2023] EWHC 1481 (Comm).


Aaron’s recent experience includes acting for:

  • London’s ExCel centre as lead claimant in London International Exhibition Centre v RSA (the ‘ATP Test Case’), named as one of the Top 20 Cases of 2023 in The Lawyer, and determined in favour of the policyholders
  • A US oil drilling company in relation to LCIA arbitration proceedings under a political risk policy issued by a consortium of Lloyd’s syndicates, arising from deprivation of assets in Russia following the commencement of hostilities with Ukraine
  • The UK’s largest pub owner in Stonegate v MS Amlin, a £1.1bn claim that tested market-critical issues of aggregation, causation and treatment of government support, and selected as one of The Lawyer’s Top 20 Cases of 2022.
  • An offshore property developer in relation to claims estimated at over £70m arising from alleged cladding defects
  • A group of over 180 restaurant owners in Policyholders v China Taiping, which reopened the question of Covid-19 business interruption coverage under non-damage denial of access clauses
  • A Saudi petrochemical joint venture on potential £120m losses arising from a cracked turbine


  • The Legal 500 recognises Aaron as a Leading Individual: “Aaron Le Marquer is the complete package: deep knowledge of both the law and the market, brilliant on strategy”;  “Aaron Le Marquer is genuinely outstanding. … A standout name in the market.”
  • Chambers and Partners Asia Pacific ranks Aaron in Band 1: “One of the legends of insurance law”.
  • Who’s Who Legal: Global Leader in Insurance and Reinsurance
  • AsiaLaw Leading Lawyers: Market Leading Lawyer (Dispute Resolution and Insurance)


Aaron trained and practised with City and US firms in London before relocating to Asia in 2011, where he spent two years in-house as regional head of litigation for a global insurer in Singapore. He then returned to private practice to lead a dedicated insurance practice at Southeast Asia’s leading law firm, with offices in seven countries across the region.

After returning to London in 2019, Aaron led the products and environmental risks practice at a leading insurance boutique, before joining Stewarts to launch the firm’s Policyholder Disputes practice in 2022.

Accreditations and Memberships

  • British Insurance Law Association
  • London Business Interruption Association
  • Law Society LGBTQ+ Solicitors Network


Aaron has been widely published and interviewed on topical policyholder issues, most recently in relation to Covid-19 business interruption coverage, and as well as featuring regularly in the insurance industry press, has appeared in publications as diverse as the Financial Times, the Hollywood Reporter, the Sun, the Telegraph and the Times.


Having originally studied music at university, Aaron enjoys playing the piano when given an occasional break by his seven-year-old twins.