Wilkins Kennedy were retained by Harlequin between 2006 and 2010 to provide financial and business advice focused on helping to build and create the Buccament Bay Resort in St Vincent and the Grenadines.

Harlequin initially sought damages of $68m for losses arising out of alleged breach of fiduciary duties and breach of contract or alternatively breach of common law duties of care in failing to perform its duties with reasonable skill and care.

According to Accountancy's Top 75 survey of firms, Wilkins Kennedy's fee income in 2015 was £37.8m.

The claim was borne out of Wilkins Kennedy’s decision to take on Harlequin’s building company called ICE as a client. At the time, Harlequin and ICE were in a bitter dispute over the costs associated with building work, but Wilkins Kennedy chose to work for both the developer and the builder at the same time, without informing Harlequin.

In a 350-page judgment, Mr Justice Coulson said Wilkins Kennedy partner Martin MacDonald and then-tax manager Jeremy Newman had shown they did not have ‘the first clue as to any rule relating to client confidentiality’.

The High Court found that both accountants at the firm then sided with ICE’s boss, Padraig O’Halloran, who misappropriated over $12m from Harlequin’s investors’ money.

The court found ‘an unusually close relationship developed between O’Halloran of ICE and MacDonald of Wilkins Kennedy’, who was referred to as Harlequin’s ‘de facto finance director’.

In 2013, O’Halloran was ordered to pay £2m that he paid into his Irish Bank accounts due to the misappropriation of several millions of pounds from the Buccament Bay project.

It was also found MacDonald, acting as the main liaison with Harlequin, had forwarded confidential documents from Harlequin’s in-house solicitor to ICE.

Harlequin founder David Ames said outside of court: ‘We have lived with the failings of Wilkins Kennedy and the nightmare of this case for years. The impact their actions have had on our investors, the success of our business, our public reputation, the happiness of our family and our own health is undeniable. Wilkins Kennedy should be holding their heads in disgrace. I trusted them as my accountants, and I cannot believe they were acting behind my back to help a fraudster get away with funding a lavish lifestyle.’

Tom Govan, communications director at Wilkins Kennedy said: 'Although disappointed that the court did not dismiss the entire case, we are pleased that it has rejected the vast majority of Harlequin’s claim. The judge has rejected all allegations brought against us, apart from one. This related to the contractual relationship between the builder and the developer, where the judge viewed both parties to have contributed equally to losses arising from deemed overpayments to the builder. We are taking legal advice with a view to appealing this aspect of the judgment.'

The full High Court judgment can be read here.