Sir Nicholas presided over a stormy period in the Revenue's history that included the tax credit IT disaster and the sale of property to a company based in a tax haven.

He joins eight other non-executives on the board, which is chaired by Roger Freeman.

Sir Nicholas had a 30-year career in the civil service, where he led the privatisation of British Rail and oversaw the competition to select an operator for the Channel Tunnel rail link.

He then spent seven years as Revenue chairman between 1997 and 2004.

Charles Lloyd, PwC corporate finance partner, said: 'Nick Montagu brings invaluable experience to further deepen the recognised expertise held by the team and offers a unique perspective on the issues around strategy, policy, financing and implementation which our clients face.'