Marr’s questions and tone were shot through with the liberal-left assumptions that hold sway at the BBC. Time and again he put words in Blair’s mouth, made facetious comments, and took cheap shots: Any regrets? Would you do it again? Anything to say to the relatives of the dead? For Marr it’s not bias, or even probing journalism, to express suspicion of and incredulity towards Blair’s arguments — it’s the default position. (At one point Marr suggested to Blair that in supporting the invasion of Iraq he stood with an American president who was “loathed” by many people in Britain. What he meant was that Bush was loathed by the left, and by media commentators and other public figures whose condescending anti-Americanism transcends political divides. The hatred eventually filtered down even to people quite ignorant of current affairs.)

Blair stuck to his guns, and the point he returned to again and again was that, yes, the war was dreadful, and yes, mistakes were made, but while he understood and respected those who disagreed with him, he wished they would at least acknowledge that those who supported the war had arguments that were worth considering, that it was “at least arguable that the world is better off without [Saddam] than with him,” and that people understood the “complexity” of the decision.

Pressed by Marr on whether he had regrets, Blair said: “You cannot possibly not feel the most immense sadness about the lives lost.” But he added: “When I’m asked whether I regret the decision, you know, I have to say I take responsibility for it, but I can’t regret the decision.” (Blair is donating all the profits from his book — his £4m advance plus royalties — to a rehabilitation center for injured British soldiers, a gesture which has only earned him more opprobrium from his detractors).

Blair’s motivation isn’t merely to account for past actions — he warned that the West would soon face a similar dilemma over Iran. He said it was “wholly unacceptable” that Iran should be allowed to develop nuclear weapons, and said the West had to be “prepared to confront them.” “Militarily?” asked Marr. “If necessary, militarily,” Blair replied. Marr was so dumbfounded by Blair’s honest and wholly undiplomatic response that he had to repeat the question. The answer was the same.

Blair referred to the wider conflict with radical Islam as a “generational struggle” and said the West should not make the mistake of thinking it was to blame for problems in the Middle East and the Muslim world. “The West’s got to resolve this debate,” he said. “Is the reason they’re like that because of us, or is it actually because of them? Now my view, in the end, is we should stop being in a situation where we think we’ve caused this. We haven’t caused this.”

Liberal-left types are of course fully aware of the “complexity” of the decisions that were taken, and are still being taken, over when and how the West should intervene to combat rogues states and terrorists. They just like to pretend that such complexities don’t exist; that there are no difficult decisions, and no consequences for doing what makes you popular, rather than what’s right. And hypotheticals only work one way, so opponents of intervention will ask “Would you do it again?” but never “What if we hadn’t done it?” or “What should be done next time?” The left has a vivid imagination when it comes to threats to liberty posed by conservative governments, or threats to the planet caused by global warming, but is unwilling to imagine what might have transpired in the Middle East had Saddam remained in power, or the consequences of Iran getting nuclear weapons.

The left can’t accept that, although they disagree with their opponents, those opponents might have a valid point, or might be motivated by something other than sinister aims. The arguments Blair advances are ones that are seldom aired outside conservative media outlets or in speeches by Dick Cheney and John Bolton. Blair has a platform that is rarely afforded to advocates of military action against Islamic extremists and their state sponsors, and his position flies in the face of the liberal-left narrative, which is why they hate him.

Blair should be commended for standing by his decisions when it would be easier to express regret and seek absolution, and as UN envoy to the Middle East his moral clarity will be vital in addressing the challenges facing the region. In an age when so many politicians are all too ready to compromise their principles to get elected, or to cling to office, he’s a striking exception.