From tonight's BBC One News at Six:
Sophie Raworth: And, John Simpson, this investigation has taken years to complete. How long-lasting will its impact be?
John Simpson: Far more than the seven years it took, Sophie. I think we're looking at decades.
Let's look at the individual elements of it.
I think you've got to go back to 1956 and the Suez campaign, which brought Britain's history as a colonial power effectively to an end, to see anything comparable.
Iraq? I go there a lot - as often as I possibly can. It's a damaged, deeply, deeply damaged society, as we saw in Jeremy Bowen's piece. The damage goes right through. It's not going to recover quickly.
The United States? Well, it got involved because after 9/11 it wanted to show it was still the dominant military power so it took on a country which looked strong but actually wasn't (Iraq). And yet, within a few years, the Americans were having to say, 'We can't fight two quite medium-sized wars at the same time'.
Britain? We'll never be quite as close to the US again - or certainly we won't just automatically follow what they do. And I think you can say there is a line to be drawn from 2003 and the invasion right through to a couple of weeks ago. That cynicism about politics in this country, I think, fed into the whole business of the EU referendum.
Sophie Raworth: Our World Affairs Editor, John Simpson. Thank you.