In future, Ineos will be audited by PwC ‘s rival Deloitte, with the change expected to take place before the end of 2019.

PwC found itself in an awkward position last February after it was revealed it had advised Ratcliffe and the chemical group’s other two other principal shareholders, Andy Currie and John Reece, on a plan to relocate their tax domicile to Monaco.

News of the tax-saving scheme raised the ire of the British public after London newspaper Sunday Times reported that while Ratcliffe and the two other men together could legally save £1 billion to £10 billion tax-free the British Treasury would lose at least £400 million and potentially be up to £4 billion short.

Reports at the time said PwC had considered severing its ties with Ineos due to the damage an alleged tax dodge might do to its reputation. The plan is said to have been flagged internally with the auditor’s UK management board.

Parts of Ineos’ operations are domiciled in the UK, but the holding is headquartered in Switzerland.

Auditing journals said Deloitte’s auditing and advisory contract could be worth about £10m. The UK’s large accounting firms are seen to be increasingly concerned about any perceived irregularities involving their largest clients in the wake of several accounting scandals.