A Big Four firm charged £1.2m in due diligence fees after saying that it could not gain access to the accounts, a senior private equity figure has said.

Jon Moulton, head of Alchemy Partners, launched a stinging assault on the value of corporate finance work carried out by the Big Four, and revealed the astonishing charge, effectively for nothing more than what he called a 'disclaimer'.

Moulton said: 'They can just issue this disclaimer, which says that they had not been able to do any validation. We're in the quite ridiculous situation that firms can say "we've done a lot less work than an audit, but we'll charge you six to ten times as much".'

The private equity boss did not name the firm in question: 'The report, from a Big Four firm, said "we've had no access to the accounting records of the company". Thank you very much for £1.2m of opinion.'

None of the Big Four would comment on the issue this week when contacted by Accountancy Age. One corporate financier said this week that a failure to gain access to the accounts was rare, but that it did happen where companies were sensitive about opening up their books to rivals. He added that the bill was 'very surprising'.

Moulton told delegates at CIMA's annual conference that there had been a complete collapse in accounting due diligence at the height of the private equity boom: 'We have seen in the last two-year bubble [of private equity buyouts] a loss of integrity in the system and we have seen excess. We have seen a complete collapse in due diligence.'

Moulton also forecast much lower fees for Big Four advisory partners as the market cooled and private equity players demanded better efforts to access company books.