The Chilcot inquiry into why Britain joined in the 2003 US invasion of Iraq may perhaps turn out to be the same sort of establishment whitewash as the three previous official investigations into more particular aspects of the scandal. Nevertheless, last Friday’s proceedings will be memorable because of the evidence presented by former Premier Tony Blair.

The suave, polished and once infinitely plausible Blair was noticeably nervous when he sat down to face six hours of questions by the five-member investigating panel led by retired Whitehall mandarin Sir John Chilcot. It did not, however, take him long before he had picked up his old magisterial style, with the seemingly thoughtful pauses between phrases, the wide-open hand gestures of innocence and that beguiling smile, once so disarming in the way it seemed to underline that he was patently telling only the truth, only common sense, as surely everyone could see.

It was a frightening display by a consummate performer, which, as it unfolded, created a rising chill in those who watched, including those seated in the same room, some families of British soldiers slain in the conflict. Blair continued to insist that at the time he believed absolutely in the WMD intelligence that later turned out to be phony. No, he had not ordered the doctoring of the intelligence. No, he had not leant on his principal law officer to have him change his original legal opinion that the invasion contravened international law, if it had not been sanctioned by the UN. And anyway, Saddam was a dangerous leader who had to be taken out. Yes, regime change was the reason for the invasion and yes, he would do it again. Indeed, said Blair in a particularly sinister aside, maybe the same action would be necessary against Iran.

At the very end of his evidence, he was asked if he had any regrets. Yes, he said and the audience held its breath. His regret was that the invasion had been so divisive in Britain. His regret was that he had not been able to persuade the public to back him in the same way that Parliament had backed him. Here he skated over the truth that British legislators only voted for the invasion because of the fraudulent WMD intelligence they were shown.

That was it. He regretted that he had failed to con a large proportion of the British — a million had demonstrated against the coming war — into supporting him. He expressed no regret for the tens of thousands of Iraqis who died in and after the invasion. He expressed no regret for terrorism breeding ground he and George W. Bush created in the ruins of the Iraqi state. And even though they sat only feet away from him, he had no regrets to give to the bereaved families of UK soldiers, even in terms of their having died “in a just war”.

This was a monstrous display of arrogance and self-justification by a man who appeared without conscience and even humanity but condemned himself with virtually every weasel word he uttered.