Tony Blair did long-term damage to trust in politics when he put forward a case for war that went beyond the "facts of the case", the author of the scathing official report into the Iraq War has said.
Sir John Chilcot, who has remained silent on the report since its publication in July, told a panel of senior MPs be believed it would take many years to repair the harm the former prime minister's actions had caused.
After an inquiry lasting seven years, the Chilcot Report found that former Iraqi dictator Saddam Hussein posed ''no imminent threat'' at the time of the invasion of his country in 2003, and the war was unleashed on the basis of ''flawed'' intelligence.
Its publication led to calls for the prosecution of Mr Blair, but the former premier insisted that, while he felt sorrow for those whose loved ones died, he stood by his decision to commit Britain to the US-led military action.
Asked if trust in politics had been corroded because MPs were told things that could not reasonably be supported by the evidence, Sir John told the House of Commons Liaison Committee: "I think when a government or the leader of a government presents a case with all the powers of advocacy that he or she can command, and in doing so goes beyond what the facts of the case and the basic analysis of that can support, then it does damage politics, yes."
He told MPs he "can only imagine" it would take a long time to repair the trust.
Sir John said Mr Blair's decision to describe the threat the Hussein regime posed as imminent had been the "best possible inflection" of the evidence he had.
"A speech was made in advocate's terms and putting the best possible inflection on the description that he used," he said.
Sir John said Mr Blair had "psychological dominance" over his cabinet ministers because of his success, which meant they did not challenge him as much as they could have.
He also agreed that the ex-PM's "sofa" style of centralised, informal government could be seen as a "21st Century equivalent of Louis XIV".
He was asked by Business Committee chair Iain Wright: "Is it almost the 21st Century equivalent of Louis XIV - 'I am the state'?"
Sir John replied: "I observed what can be described in that way.
"I think it reached a high point in Mr Blair's prime ministership and I've got a memory from taking evidence from his foreign secretary, from Mr (Jack) Straw, when we asked how was it that members of the cabinet, other than Robin Cook, and to a lesser extent I suppose Clare Short, did not provide more challenge and insist on debate and insist on information."
"They were promised it sometimes, but the promises were not delivered.
"And the answer that came back was quite simple, it was that Tony Blair had, as leader of the opposition, rescued his party from a very dire political predicament, and he'd done it again afterwards as prime minister.
"And I had the sense from Mr Straw's reaction that he had achieved a personal political dominance which was itself overriding the doctrine of collective cabinet responsibility."
Sir John added: "Patronage particularly perhaps, but also just sheer psychological dominance - 'he'd been right, was he not right this time'?"
Sir John sidestepped questions over whether the war was legal, telling MPs the inquiry had not been "in a position" to offer that opinion.
He said: "The process by which the view was reached by the British government and its principle legal adviser, the Attorney General, we thought was unsatisfactory and deficient in more than a few respects.
"That did not enable us to come to the conclusion the war was not lawful but neither did we say that we endorse that advice or the way in which it was evolved and shared with government and that's as far as I can take it."
Asked if a reasonable person would have come to the conclusion that it was an illegal war, he replied: "I think that reasonable person would have to be brave as well as reasonable."
Sir John dismissed suggestions that the so-called Maxwellisation process, which allowed individuals facing criticism the chance to respond before the report was finalised, had delayed its publication.
"I think in the pursuit of fairness, but also the pursuit of getting the best possible quality of report, I think the Maxwell process, far from holding up the show actually improved the eventual outcome.
"Our attention was brought to documents which hadn't been either disclosed or discovered in the course of our other evidence taking which was relevant."