Chilcot on Blair, Bush and the Iraq war - a year on
The Chilcot report became a by-word for dispute, delay, and doubt.
When the inquiry finally emerged in its full two million words, in the chaotic aftermath of the EU referendum, its analysis was polite.
But it was firmly critical of the decision-making process and behaviour of the UK government both in the run-up to, conduct of, and aftermath of one of the most controversial conflicts in British foreign policy - what many now regard as one of the UK's biggest foreign policy mistakes.
In the immediate aftermath of the inquiry itself, Sir John, a former Whitehall permanent secretary who had worked for decades at the highest level of government, declined to take further part in the debate, as his and his panels' conclusions were digested.
But in the run-up to the report's anniversary, he agreed to speak for the first time about the inquiry's conclusions, its criticisms and consequences for us all.
Exactly a year ago, he produced two million words in 12 volumes, to detail a seven-year long study of the tumultuous political and diplomatic events in the run-up to, conduct, and aftermath of the 2003 Iraq War.
But what was implicit in the lengthy pages of that document is now crystal clear in his personal, succinct and unvarnished view of the hours of evidence, thousands of documents, and witness accounts of one of the country's most significant public inquiries.
He defends its duration, its conduct, and believes strongly that the work could stop another rush to war in the future.
Sir John told me believes the "rising generations" of the military have understood and absorbed the lessons of the inquiry so much that they would demand and insist that future governments would be required to be more rigorous, more thorough in their examinations of the case for war.
He explained his exhaustive criticism of the relationship between Tony Blair and George W Bush, his shock on seeing their private correspondence for the first time. He also spoke of his own relief at how the families of those killed in the conflict received his report when it was finally published.
But he speaks plainly on perhaps the most fundamental political question of all, the role of the former prime minister. When asked if Tony Blair had been as straight with the country and the inquiry as he ought to have been, Sir John told me, 'any prime minister taking a country into war has got to be straight with the nation and carry it, so far as possible, with him or her. I don't believe that was the case in the Iraq instance."
He went on to say he believed Tony Blair had given an "emotional truth" to the inquiry, and had been "suffering" during its sessions - Tony Blair was always, he said ,"the advocate" for whom, "persuasion is everything".
A spokesperson for the former prime minister referred us to his comments when the inquiry was published, when he said the report showed there were no lies, and no deceit, but that he took responsibility for the criticisms of how decisions had been made.
You won't be surprised, having undertaken such a huge task, that Sir John speaks on a massive range of issues concerned with the Iraq war.
The conflict may have begun 14 years ago now, the inquiry taking longer than the war itself. But for our politics, our diplomacy, and our military, this new more personal account will still resonate today.