By BBC News Online's political correspondent Nick Assinder

It was the moment the great Labour control machine finally fell apart and Tony Blair was left floundering like a goldfish thrown out of its bowl.

The prime minister was on his feet during question time, clearly thinking he was, for once, giving William Hague a run for his money.

The opposition leader was harrying him over the continuing row about funding for Wales and Plaid Cymru's plans to force a vote of no confidence in Labour's assembly leader Alun Michael.

But Mr Blair was clearly confident that he still had a grip on Wales and, even if Mr Michael was forced to quit, he could reinstate him almost immediately. And, in any case, who cared?

Suddenly, out of the backbench gloom, a Tory bleeper sounded - "tell William Hague that Alun Michael has quit", it announced.

Mr Hague was, at first, reluctant to believe he was the first to hear the devastating news that the beleaguered Labour leader of the Welsh assembly had fallen on his sword.

After all, just minutes before the prime minister had told him: "I believe the Welsh first secretary is doing a good job."

Direct hit

But Mr Hague took a punt anyway and asked Mr Blair: "Will you comment on the fact that within moments of you expressing your full-hearted confidence in Mr Michael five or 10 minutes ago ... news came through to the House that Mr Michael had resigned before the vote of confidence had been taken?

"Will you confirm to the House whether or not this has actually happened and if it has, will you confirm as well that the next big test of devolution will be the choice of a new First Secretary without any interference whatsoever from you?"

It was a direct hit and the prime minister appeared genuinely thrown off his stride.

He flammed and he ducked, but he did not answer the question, simply stating: "The one thing we can be sure of is that it won't be a Tory!"

Never before had he looked so flummoxed at question time.

It was up to his spin doctors to later try and regain ground by claiming he had spoken to Mr Michael two hours before the humiliating clash and agreed Mr Michael's strategy.

'Back to square one'

Mr Blair, they claimed, was not able to announce it until Mr Michael has formally quit. But that cut little ice in Westminster.

The overwhelming impression was that the prime minister had no idea what was going on and had been caught on the hop.

What is worse for the government than the bad publicity, however, is that it is now back to square one on Wales.

Rhodri Morgan - the man Downing Street pulled out all the stops to prevent becoming leader - is now acting leader and there is every chance that he will be Mr Michael's successor.

The row has not only severely damaged Labour's devolution policy but also undermined Mr Blair's leadership credibility.