The owners of the London Stadium and their advisers Big Four firm PwC were responsible for negotiating a loss-making deal to lease out the ground to Premier League football club West Ham United, Magic Circle law firm Allen & Overy (A&O) has said.

The stadium’s public sector owners E20 and London Legacy Development Corporation (LLDC) launched a £12m claim against their former law firm A&O in September, alleging it was negligent in the drafting of the 2013 concession agreement that governs West Ham’s 99-year lease of the ground in the Olympic Park in Stratford.