Philip Webster, Political Editor of The Times, explains why Mr Blunkett had to go and what effect his departure will have on the government and Tony Blair

"I'm not at all surprised that Mr Blunkett has gone - I am only surprised that he managed to cling on until today.

"His resignation has looked virtually inevitable since the weekend, but I understand there may well have been a straw that broke the camel's back. I understand that there may have been other business appointments that have not been declared.

"Whether in themselves they are that serious I do not know - he may have forgotten to register certain other financial affairs - but coming on the back of everything else, it left Blair with no choice but to cut the rope.

"Even without these, however, the opinion among Labour backbenchers was such that Mr Blunkett would have found it very hard to survive for long. Mr Blair was due to meet the parliamentary committee of backbenchers later today and they would have told him blankly that Mr Blunkett's position was untenable.

"The reason for that general feeling was not so much that Mr Blunkett has breached this or that regulation; it was the general issue of his judgement in taking the job and buying shares in the middle of an election campaign.

"Everybody in the country knew that he was soon due for a recall to the Cabinet and, for the Labour backbench, his diving-in to make a quick bit of cash before going back to a senior position smacked rather too much of sleaze.

"We will find out whether or not there was a smoking gun later today, but one thing that is certain is that he won't be coming back. We have learned with Peter Mandelson that to resign once is serious, but to resign twice is terminal.

"Blair will carry out a swift re-shuffle. By the end of today we will have a new Work and Pensions Secretary. He will certainly go for a Blairite moderniser and it could well be David Miliband.

"Whoever it is will be presented with an immense in-tray of work second only in size and controversy to Ruth Kelly's portfolio at education. Not only is there the pensions reform. The Adair Turner report is due in the next week and Mr Blunkett was preparing to release the controversial White Paper on welfare and benefits reform.

"This is very bed news for Blair. He has been seen to hang on to Mr Blunkett for as long as he can to justify his decision to bring him back. The view among MPs is that he brought him back too hastily, before he had really earned his re-call to the Cabinet.

"On May 6, Blair was in a very strong position after winning the election and could do what he liked: the decision does not look so clever now.

"No doubt, Michael Howard will also recall some of Tony Blair's earlier statements about the Labour government being 'whiter than white'.

"The question of what Mr Blunkett will do now, obviously no-one knows Clearly his priority will be to make money. In his six months out of office he was keen to take those jobs which ultimately led to his resignation today."

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