Former Downing Street communications chief Alastair Campbell broke down on television as he defended Tony Blair against claims he misled Parliament over the case for war in Iraq.
Mr Campbell insisted the former prime minister was a "totally honourable" man in an extraordinary appearance during which he frequently had to pause to compose himself.
He later claimed that he had been upset over a perceived slight comparing his latest novel Maya to the controversial dossier on Saddam Hussein's weapons of mass destruction.
The BBC's Andrew Marr introduced Mr Campbell to talk about his "new work of fiction" - which the former spin doctor took as a barbed reference to the dossier.
Mr Campbell gave evidence to Sir John Chilcot's Iraq Inquiry last month but later issued a clarification about his answer to one of the key questions, saying he feared he had given the wrong impression that the then prime minister could have claimed Saddam Hussein had weapons of mass destruction "beyond doubt" even if intelligence chiefs disagreed.
Mr Marr asked him: "If beyond doubt is not established in the intelligence when this inquiry looks at the intelligence, does it then follow, yes or no, the prime minister misled Parliament?" Mr Campbell replied: "The prime minister did not mislead Parliament."
But he was pressed on whether that was the case even if the intelligence did not confirm the assertion.
Mr Campbell began to reply before pausing and appeared to be struggling for breath. "Yes, because I said ... forgive me for this, I've ...". Mr Marr told him "people say you can't answer this question".
Mr Campbell again gave a reply interrupted by several pauses, saying: "I've been through a lot of this Andrew. And I've been through a lot of that inquiry ... and, er ... Tony Blair, I think is a totally honourable man."
Mr Campbell hit out at the "vilification" he had received along with Mr Blair over the conflict and the controversial September 2002 dossier of intelligence. "You did it again this morning, which is probably why I'm a bit upset, this constant sort of vilification," he said. "You compared the novel to the dossier, that it was all fiction and all the rest of it. It's not. I'm sorry if I do get upset about this but I was there alongside Tony, I know how that decision weighed on him, I know the care that we took."