The average profit per equity partner fell by £20,000 to £323,000 for the year to June, according to an interim transparency report published by the mid-tier accountancy firm.

Profits at the audit division decreased by 60% to £5.4 despite turnover in line with the previous year at £131.7 million. The firms total UK revenue increased by 2.2% to £502m.

The interim transparency report, first reported by the Financial Times, said that Grant Thornton will postpone the publication of its accounts because it has moved its accounting period from June to December to align the business with its global reporting commitments.

The Times reported that Grant Thornton has been in the spotlight throughout 2019 over its role as auditor of Patisserie Valerie. Its audit work on the chain, which fell into administration following a £40m hole was discovered in its accounts, is under investigation by the Financial Reporting Council, the audit regulator.

The FRC has put the firm under scrutiny and called its performance “unacceptable” because of its continuously poor results in an annual assessment of Britain’s biggest audit firms. The examination scrutinised a sample of 0.6 per cent of Grant Thornton’s audit work.

In February, the firm was ordered by a court to pay over £21m in damages to Assetco, its former client, which almost collapsed in 2011 amid an accounting scandal, for negligence “of the utmost gravity”. Grant Thornton is appealing.

Grant Thornton has also experienced a shake-up in its leadership when Sacha Romanovitch resigned as chief executive in October last year after senior partners claimed she was not focusing on profits.

A total of 12 partners left the firm and between 50 and 60 members of staff in marketing and communications, roles were let go.

With the FRC increasing penalties levies on firms that conduct poor quality audits, Grant Thornton has decided to resign from auditing companies that are deemed to be riskier or less lucrative.

In August, the company resigned as auditor of Sports Direct.