The suggestion came as speculation grew that Sir David had been pushed out at HM Revenue & Customs amid issues over the credits, carousel fraud and the perceived increase in aggression of the department.

The body is also thought to be suffering from managerial issues, with the huge over-subscription of an ‘ungenerous early retirement scheme,’ as one Whitehall source described it. The merger of Revenue and Customs, sources said, has led to confused accountabilities at the department.

Sir David’s apparent difficulties are being seen as a blow to Treasury initiatives to move private sector talent into government. His appointment in 2004, from mm02, was a significant coup in attracting business leaders.

The move means two private sector figures – James Sassoon (formerly of UBS) and Sir David – have now stepped down from positions at the Treasury and HMRC to take on advisory briefs. Sir David is now advising on ‘transformational government strategy’.

Whitehall sources indicated they would not be surprised to see Gray, Sir David’s deputy, appointed. Gray has experience at the Treasury, the DSS, as it was, and the Department for Work and Pensions.