Whistle-blower's identity a mystery

David Blunkett went on the offensive yesterday to deny any involvement in the leaking of his memo to Gordon Brown. The memo was written a fortnight ago, on the eve of a Commons vote on plans to curtail lone parents' benefits, and if Mr Blunkett had chosen to leak it he might have been expected to have done it sooner.

Copies were sent to the Prime Minister, Harriet Harman, John Prescott, Alistair Darling, Donald Dewar, Ron Davies and Mo Mowlam, so there could be any number of suspects. The number with access to Mr Blunkett's memo were certainly in double if not treble figures.

"I am extremely uncomfortable with a system which results in my private memoranda to cabinet colleagues being leaked to the papers. If there's a lesson ... it's not that we don't have vigorous debate or that we don't present to each other what we think, it's that we don't do it in writing," Mr Blunkett said.

Yesterday a sceptic said leaking the memo might not do Mr Blunkett any harm politically. Despite his alliance with Tony Blair and high-profile agenda on raising schools standards, he has maintained some support from the old left in his party. The revelation that he has protested against the suggestion that disability benefits should be cut across the board will strengthen those links.