Tony Blair failed properly to discuss plans to join the US-led invasion of Iraq because he did not trust Cabinet colleagues not to leak discussions, the UK's top civil servant has said.
And Cabinet Secretary Sir Gus O'Donnell told the Iraq Inquiry such an informal approach meant there were insufficient records to fully examine the decision to go to war.
Sir Gus levelled a number of criticisms at Mr Blair's so-called "sofa government" style as he was quizzed by the Iraq Inquiry, which is shortly to conclude its evidence gathering.
The then prime minister's distrust of colleagues meant he did not consider the Cabinet the "safe space" it ought to be for the frank discussion of key policies, he said.
And failing to provide Cabinet colleagues with the full legal advice of the attorney general on important decisions was contrary to the ministerial code, he said.
Lord Turnbull, who was cabinet secretary at the time, told the inquiry this week the Cabinet was deprived of key papers outlining options and was "imprisoned" into backing the war.
He rejected assertions by Mr Blair, when he was recalled before the Inquiry last week, that his Cabinet colleagues all "knew the score" and that there were frequent discussions of the issues.
Sir Gus, who was at that time the top official at the Treasury, said frank discussions within Cabinet leading to an agreed line were the ideal formula for the best decision making.
But Mr Blair preferred to keep discussions to more exclusive groups, in part because distrust of colleagues meant he did not consider it the "safe space" it should ideally be, he said.
The Inquiry was adjourned until next week, when the foreign secretary at the time of the invasion, Jack Straw, is among the last scheduled witnesses.