Many may disagree, says Blair, but you sense that he doesn't greatly care

There was a moment at the heart of the interview when it sounded as if Andrew Marr might have borrowed a question from David Frost – his now famous suggestion to a disgraced ex-president that there was something the American people very much wanted to hear him say. The subject here, of course, was Iraq: "To all the people, looking, watching who still feel very angry and upset about this," Marr asked, "is there anything further that you want to say to them?" Mr Blair – it won't greatly surprise you to learn – declined the invitation to play Nixon. It would be inhuman not to feel sorry about those who had died, he agreed, but no, he didn't regret the decision he'd made about war.

As became clear over the course of an interview that was an odd mixture of pre-trial hearing and book puff, categorical certainty remains a crucial part of Mr Blair's psychological armoury. His metaphors are categorical too – even if their certainty doesn't always square with the argument that comes next.

"I always took the view that if we departed a millimetre from New Labour we were going to be in trouble", he said about the last election. What, not even a millimetre of leeway? And this from a man who elsewhere argued that the Labour Party must always remain adaptable.

The party, he said, could count on his "one hundred per cent support" – a percentage still quite high enough, apparently, to justify no harsher verdict on the Conservative- Lib Dem coalition than that it was "too early to say".

He looked a younger, more contented man than the one who left Downing Street three years ago. Money clearly agrees with him – and the fact that he doesn't have to bother with the febrile defensiveness of day to day politics. The hand gestures were the same – and many of the rhetorical tics. Several times we got the Blair "look...", that verbal signpost he uses to suggest that he's shifted up a gear in sincerity in order to get up a difficult slope. But he's willing to admit to error these days as long as they're small ones. He owned up to lying (little white ones in the cause of peace in Northern Ireland) and he admitted to policy mistakes (fox hunting, and not much more). On Iraq though he remains almost serenely convinced of his rectitude – never embattled but occasionally incredulous that other people still don't get it.

In an interview this wide-ranging it was never going to be possible to conduct a forensic cross-examination. So some of Mr Blair's odd inconsistencies passed unchallenged. Talking of Gordon Brown's ambitions he said he would have gone earlier if he had been sure that the reform programme would stay in place, and yet, just a little later, "if I had thought I literally couldn't get the reform programme through I would have gone rather than stayed".

He was in favour of the state fashioning structures that put power in the hands of people, but not, it seems, when that power was in the form of information that might threaten the power of the state. That would leave some people aghast, said Marr – but other people's aghastness is something that Mr Blair has acquired a taste for. "Some of politics is right versus left", he said at one point, "and some of politics is right versus wrong". He had left the first kind behind him, he implied, and he's in the right party on the second. "Many may disagree", were his final words. Many almost certainly do – but you sense Mr Blair doesn't greatly care.