WITH David Blunkett departing the Government - as we said he should - the question now being asked is how much damage his resignation has caused the Prime Minister?

Tony Blair has been lucky during his years in Downing Street to be faced with a weak Opposition. But he has been unfortunate to be let down by his most trusted allies.

Like Peter Mandelson before him, David Blunkett enjoyed more support from Mr Blair than his failures of judgement deserved.

The Prime Minister did everything he could not to lose his friends from his Government, desperately trying to protect them from the storms they managed to whip up for themselves, then giving them second chances.

When those second chances were blown by further misjudgements, it was bound to reflect on the Prime Minister who placed so much faith in them.

From the moment Sir Alistair Graham, chairman of the committee on standards in public life, declared that Mr Blunkett had undoubtedly breached ministerial rules, it should have been obvious that there was no escape.

And yet Mr Blair maintained in the Commons yesterday that Mr Blunkett did not deserve to be sacked under the ministerial code.

"I could discover no impropriety or wrong-doing," said the Prime Minister.

If that is so, why have a ministerial code in the first place, and why have a committee to police it?

There are times when loyalty to a friend has to give way to reality. And the reality is that David Blunkett's brilliance, like Peter Mandelson's, was undermined by arrogance and a complete failure to sense how the public would perceive his actions.

Tony Blair's credibility has inevitably been undermined as a result.