At the end of a week in which Gordon Brown has been pushed on to the ropes over the parliamentary sleaze row, Thursday’s intervention by Standard & Poor’s, the ratings agency, may have been the most wounding blow of all.

To a man who forged his reputation for so many years on his seemingly astute handling of the British economy, its decision to shift the outlook for the UK from stable to negative may have proved at least as distressing as the revelations about expenses claims that have dragged politics into the mire.