By Nick Assinder BBC News Online political correspondent

Blair showed no signs of doubt

On key issues such as the war on Iraq and weapons of mass destruction, Europe and the euro and a host of others he has seldom appeared more certain.

He told the senior MPs he stood 100% by his decision to go to war.

He flatly rejected the foreign affairs committee's finding that the jury was still out on weapons of mass destruction, insisting they would be found.

He refused to offer an apology for the dodgy dossier or admit he had misrepresented it to the Commons.

And he proudly declared he had "done the right thing" over Saddam Hussein.

Supremely confident

On Europe, he offered unswerving support for the creation of an EU president while equally enthusiastically rejecting demands for a referendum on the new EU constitution.

And he once again expressed his personal enthusiasm for the single currency.

Voters are concerned over the war on Iraq

The caveat that he would only join when the economic circumstances were right appeared more ritualistic than ever before. That will get under Gordon Brown's skin.

And on a host of other issues from constitutional reforms to the "botched" cabinet reshuffle he presented a sure, unbending, supremely confident image.

The fact that he managed to keep it up for 150 minutes was just as impressive as the fact that he could do it at all.

His appearance came against a background of growing public doubts over the legitimacy of the war on Iraq and his and his government's trustworthiness.

By any measure, he is suffering the most difficult period of his premiership, with voters still demanding the long-promised delivery of election pledges.

Too polite

He has a growing band of dissidents on his own benches and in the wider Labour movement demanding a return to core values.

And he is facing serious battles ahead over public sector reform, notably over foundation hospitals, tuition fees and even fox hunting.

But if it is all starting to grind him down there was no sign of it here.

Admittedly, partly because of the nature of the occasion, the committee members did not give him a particularly difficult time.

And, of course, he regularly resorted to his habit of answering different questions to the ones he had been asked.

They are too polite and serious for rough-housing and the format of the session makes it difficult for sustained cross examination on any single issue.

That is not to say there were not some uncomfortable moments for the prime minister. There were - notably over weapons of mass destruction and whether, if they were not found, it would destroy the legitimacy of the war.

Key questions

And, particularly at the start of the session, he looked uncertain, almost nervous. But that didn't last long.

It was soon replaced by certainty, barely-concealed anger and occasional dismissiveness.

And, of course, he regularly resorted to his habit of answering different questions to the ones he had been asked.

That regularly leaves his interrogators dissatisfied and frustrated - just ask Iain Duncan Smith who gets it on a weekly basis.

And, on this occasion, it meant some key questions about weapons of mass destruction in particular, were left hanging.

But this was another psychologically important occasion for Mr Blair and his government as they try to get back on track.

However, the question on many minds after the session was whether this had been a display of self-confidence or self-delusion.