One of Britain’s richest financiers is taking his former barrister to court, alleging negligent legal advice in a long-running tax dispute. The case highlights the significant professional liability facing specialist tax counsel when aggressive financial structures unravel.
Michael Platt, the billionaire founder of BlueCrest Capital Management, has brought professional negligence proceedings against leading tax barrister Malcolm Gammie KC of One Essex Court (Above).
The claim, filed in September 2025, follows BlueCrest’s lengthy battle with HM Revenue & Customs over the tax treatment of payments made to senior traders under its partner incentivisation plan.
Gammie represented Platt, BlueCrest and former finance chief Andrew Dodd during earlier tribunal proceedings. The dispute subsequently reached the Court of Appeal in 2023, where BlueCrest suffered a significant defeat over the taxation of the incentive payments.
According to City AM’s report, the negligence claim centres on whether Gammie should have advised his clients to advance arguments based on their Swiss tax residency.
Platt and BlueCrest allege that the failure deprived them of an opportunity to pursue a different defence against HMRC.
At a Commercial Court hearing on Friday, 6 November, lawyers also disputed whether bank and credit card statements dating back 17 years should be disclosed as evidence.
The proceedings come after another major setback for BlueCrest. In July, the UK Supreme Court rejected the firm’s arguments concerning the employment tax status of its LLP members, potentially exposing it to a tax bill approaching £200 million. That ruling concerned a separate tax issue from the one underlying the negligence claim.
The allegations against Gammie remain unproven. No trial date has been set.
