Yesterday's Commons debate revealed the truth of Blair's weakened position

Michael Howard resorted to the rapier in comparing his own unpopularity when he was Home Secretary to that of the Prime Minister now

All too rarely, the House of Commons still has the capacity to electrify. Yesterday managed to be one of those occasions. So comprehensive had been Tony Blair's obliteration of Michael Howard on the back of the Government's spectacular exoneration by the Hutton report that the debate scheduled for a week ahead looked to be no more than a formality, a needless demonstration that a battered but unbowed Prime Minister had recovered his mastery of the political landscape.

Three factors conspired to change that benign outlook even before we got to yesterday. The first was the rapid public recognition that the Hutton report had actually been too good for the Government, the credibility of its serious and justified criticisms of the BBC undermined by the almost total absence of parallel (even if lesser) criticisms of the Government.

The second was the needless and hubristic television performance by Alastair Campbell shortly after the report's publication, in which the Prime Minister's former director of communications was allowed to damage the Government's cause by publicly calling for more BBC heads to roll. He wasn't quite swift enough to contaminate the resignation of the BBC chairman Gavyn Davies, an honourable man who distinguished himself by taking the - nowadays wholly exceptional - view that the top man was, in the end, the one to go, and who was generously willing to make a swift sacrifice in the hope that the job of the Director General Greg Dyke could still be saved. But Campbell was swift enough to make it look irresistibly as if the BBC governors' ready acceptance of Dyke's subsequent resignation was a scalp for a bullying government even if it wasn't.

And the third was George Bush's decision, precipitately announced on Sunday with a brutal lack of consultation with London, to allow an inquiry into the non-discovery of WMD. This was not only because it put the Government on the defensive and necessitated a Blair U-turn, but also because it served as a potent illustration of the US administration's unwillingness, in the face of raw domestic politics, to help the British government in return for all its past loyalty.

That Howard yesterday successfully milked this last point - which particularly resonates among Labour MPs - exemplifies a skilful and good-humoured Commons performance that could hardly have contrasted more sharply with last week's dismal flop. He managed, at least to the satisfaction of his own MPs, to survive the Hutton-underpinned onslaught against his perilous attack on the truthfulness of the Prime Minister's public statement that he had not authorised the leak of Dr Kelly's name. He tellingly endorsed the proposal by the Defence Intelligence Staff expert Brian Jones in his gripping Independent article yesterday that Tony Blair publish the ultra-secret MI6 intelligence that supposedly clinched the argument that Saddam had WMD. And he resorted to the rapier in comparing his own unhappy divorce from the public mood when he was an unpopular Home Secretary to that of the Prime Minister now.

This doesn't mean that Howard was exactly a victor, and would not have done even if Blair had not also turned out one of his most accomplished performances. Howard must worry that by signing up to Lord Butler's inquiry into the intelligence on WMD he has fallen into a trap.He has gambled with a relatively thin hand. Having secured no more than a formal commitment that the inquiry will be allowed to make recommendations on the "use of" intelligence, he is assuming that it will open the way to a full-scale investigation of Downing Street's role in the compilation of the dossier of September 2002.

On the other hand it's just possible that Lord Butler will not be quite the patsy he has been widely portrayed as. Yes, he took the word of the miscreant Tory minister Jonathan Aitken when it proved to be worthless. Yes, he memorably scandalised civil servants by suggesting to Sir Richard Scott's arms-to-Iraq inquiry, in defence of government obfuscation, that "half a picture can be true". But Lord Butler has a visceral and highly political intelligence. He can see how the Hutton report was received. He is known to harbour private concerns about the politicisation of the civil service. And he will be wary of a report whose credibility might be lethally undermined if, as is quite possible, something more robust and damaging emerges later from the US investigation. And that may mean a more critical look than Hutton at the editorial role adopted by Downing Street in relation to the published intelligence on WMD.

So Howard lives to fight another day. Why should events in the House of Commons matter when most people outside Westminster will barely notice them? The answer lies in the extent that they reflect a wider political truth, which Howard has begun to scent, about Blair's problem with his own MPs, as well as the electorate.

There are big caveats here. The BBC's handling of Andrew Gilligan's wrong - badly wrong - report that Downing Street had inserted intelligence judgements it knew to be incorrect in the dossier deserved the condemnation it got from Lord Hutton. The starting assumption that politicians are lying - itself one of the most over-used terms in current political discourse - is often a disastrous platform from which to search for the real, complicated truth. And in passing, it was worth saying, as the Labour MP Clive Soley did yesterday, that the shopping of David Kelly's name to MPsby Gilligan was an inglorious moment.

Secondly, however startling Blair's admission that he did not know the exact nature of the threat described by the 45-minute claim, it was hard not to be impressed by his peroration. All the evidence is that he believes as sincerely as ever that it was right to go to war, and that history and a peaceful Iraq will, in the end, vindicate him.

But Downing Street played a big part in the collapse of trust. The failure of Alastair Campbell to tell the Foreign Affairs Select committee what he finally told Lord Hutton, that he had secured changes in the exact wording of the 45-minute claim, is illustrative. Every journalist, including Campbell, is familiar with the problem: the reporter is asked by his immediate editor if he can harden up his story. He enters a negotiation and, if he is really unhappy with the outcome, takes his name off the story. The fact that John Scarlett kept his byline on the story does not alter the fact that No 10 is paying the price for what looks all too like aggressive editing.

It may be better in the end for the Blair Government if Butler is given the freedom to test this suspicion about what happened to destruction in order that lessons can be - publicly - learned. The Commons debate mattered yesterday because it went to the heart of what has most scarred an in many ways good government: a raging addiction to spin and a belief that the decision to go to war was dictated by Washington. The path of recovery from this looks less clear than it did even a week ago.

d.macintyre@independent.co.uk