In his long speech following the release of the Chilcot report, Tony Blair's own magic turned against him

The more he pleaded for his character, using the same arguments that have become so familiar over 13 years, the more he guaranteed Thursday’s venomous front pages

It was a bad idea for Tony Blair to give his two-hour response to the Chilcot report on Wednesday. His office had already put out a short statement drawing attention to the findings that he thought were important, mainly that he hadn’t lied, hadn’t used intelligence improperly and hadn’t made a secret commitment to war.

That would have been quite enough. Not that it would have made much difference to Thursday’s headlines, the British press at its poisonous worst. If he hadn’t appeared in public to say anything the headlines would have been: “Blair in hiding as Chilcot delivers damning verdict.”

If he had simply paid his respects to the fallen and their families and published his 6,000-word speech as an article, some of its words would have been made to fit the story that the press wanted to write anyway.

What he chose to do, though, was probably the worst option. A virtuoso show of the emotional torment of having to live with a difficult and unpopular decision taken many years ago, followed by a long apologia – “a formal written defence of one’s opinions or conduct”, from Greek, “a speech in one’s own defence” – and questions from journalists.

The old skills were still there. I still remember the moment in 1992 when I decided I was going to write a book about him. I was interviewing him in his Sedgefield constituency for a BBC programme about Labour’s future after four election defeats. A diffident and brittle front-bench MP had suddenly matured into one of the most gifted televisual communicators British politics has known. He spoke in clear non-political language with transparent conviction.

For a long time that magic sustained the New Labour project, until around 2000 when its very success started to undermine it from within. New Labour acquired a reputation for “spin”, which was evidence of how bad it was at spinning, and the nation started to tire of Blair’s blazing sincerity.

In 2003, his persuasive powers earned him – just about, and reluctantly – one last chance. Most of the press uneasily supported the war in Iraq, but when it started to go wrong there was hell to pay.

The Great Persuader’s afterglow was enough – just about, and reluctantly – to get him over the line in the 2005 election. But the magic had gone. By Wednesday’s press conference, it had become properly radioactive. The skills of oratory and persuasion were still there, but they had become their opposites. The more he pleaded for his character, using the same arguments that have become so familiar over 13 years, the more he guaranteed Thursday’s venomous front pages.

I can see why he wanted to do it. For seven years he has had to give partial defences of his position followed by saying that people would have to “wait for Chilcot”. When the wait was over, he wanted to give a comprehensive response, and to invite questions about it.

This made the elementary mistake of assuming that because Chilcot was a definitive account accompanied by the full disclosure of all the documents, it would be received by journalists as the basis for a thorough and balanced discussion of the exam paper, “British foreign policy towards Iraq, 2001-09.”

Naturally, the response of most newspapers to a 2.6-million-word report was “tl;dr, Blair very bad”. The spell is well and truly broken now.

It wasn’t sensible to engage with the meaningless “would you do it again?” question. But he did, and gave the Daily Mail, the Express, The Daily Telegraph and the i paper their headlines. To say he would do the same again if he were provided with the same information is a statement of the obvious that can be made to look – talk about spinning – as if he glories in the death and destruction.

The rest of the newspapers went with the publication of the note to George W Bush that has been known about since October 2003: “I will be with you, whatever.” This allowed them to contradict Chilcot’s finding that there was no secret commitment to war on their front pages.

Seven years and they just publish what they have always thought. I don’t know why Sir John and his colleagues bothered.

I have long been in the strange position of disagreeing with most of my colleagues about Blair and Iraq. And I have spent much of the time since 2003 trying to understand what lies behind what seems to me the disproportionate rage against him.

Yes, Iraq has been a disaster, and Blair’s proud refusal to accept that it was a bad decision is provoking, but there seems more to it. Maybe it is that hopes were once so high, that people feel they were taken in, and that the press has a feral tendency to tear to shreds those whom it once extolled.

His reputation in history was already going to be dominated by Iraq. The Chilcot report has sealed that for him. Not just by its hostile verdict, but because it has unleashed another wave of unreason. The report says that there was no deception (except Saddam Hussein’s), yet “Weapon of Mass Deception” was The Sun’s headline.

He will still be admired abroad. In Kurdistan, Kosovo and Sierra Leone he is a hero. His stock is high in America and Australia, where the intensity and duration of our Iraq War introspection is viewed with bemusement.

But having been one of the country’s most successful and popular prime ministers, he is now, permanently and unfairly, without honour in his own land.