So now it emerges that Sir Richard Dearlove deliberately misled Blair 
http://www.thetimes.co.uk/article/spy-chief-did-not-tell-blair-about-lies-of-key-source-c6grtpsqd (subscription) Also detail referenced in this source
The head of MI6 told Tony Blair that he remained confident about intelligence on Iraq’s weapons of mass destruction despite knowing that a key source was a proven liar, the Chilcot report reveals.
Sir Richard Dearlove backed the intelligence on Iraq in a letter to the prime minister in July 2003, 24 hours after MI6 quietly withdrew a claim that Saddam Hussein was still making WMD. The agency had concluded that its source was “a fabricator who had lied from the outset”. It even believed that his claims may have been inspired by a fictional chemical weapon in the American action film The Rock.
MI6 did not tell Mr Blair that the source had been discredited. The prime minister only found out several months later as a result of a Whitehall review on the handling of intelligence about Iraq.
So maybe if anyone it is Dearlove that needs to go to jail, go directly to jail and not pass Go. Certainly a case to have his knighthood AND pension removed
Bliar: "Now then Richard, don't tell me you have any doubts about this WMD business, I have promised to go to war alongside Bush"
Dearlove: "Well PM, we are no longer so sure..."
Bliar: "Didn't you hear me man? I said
don't tell me"
Dearlove: "Yes, Prime Minister"