Smash hit

"[Blair replied:] 'Yes, but all the effort he has had to put into concealment makes it difficult for him to assemble them quickly for use'."

Cook continues: "There were two distinct elements to this exchange that sent me away deeply troubled. The first was that the timetable to war was plainly not driven by the progress of the UN weapons inspections. Tony made no attempt to pretend that what Hans Blix [the UN's chief weapons inspector] might report would make any difference to the countdown to invasion.

"The second troubling element to our conversation was that Tony did not try to argue me out of the view that Saddam did not have real weapons of mass destruction that were designed for strategic use against city populations and capable of being delivered with reliability over long distances. I had now expressed that view to both the chairman of the JIC and to the prime minister and both had assented in it.

"At the time I did believe it likely that Saddam had retained a quantity of chemical munitions for tactical use on the battlefield. These did not pose 'a real and present danger to Britain' as they were not designed for use against city populations and by definition could threaten British personnel only if we were to deploy them on the battlefield within range of Iraqi artillery.

"I had now twice been told that even those chemical shells had been put beyond operational use in response to the pressure from intrusive inspections. I have no reason to doubt that Tony Blair believed in September that Saddam really had weapons of mass destruction ready for firing within 45 minutes. What was clear from this conversation was that he did not believe it himself in March."

Cook asks: "If No 10 accepted that Saddam had no real weapons of mass destruction which he could credibly deliver against city targets and if they themselves believed that he could not reassemble his chemical weapons in a credible timescale for use on the battlefield, just how much of a threat did they really think Saddam represented?"

He raises "the gravest of political questions. The rules of the Commons explicitly require ministers to correct the record as soon as they are aware that they may have misled parliament. If the government did come to know that the [United States] State Department did not trust the claims in the September dossier and that some of even their top experts did not believe them, should they not have told parliament before asking the Commons to vote for war on a false prospectus?"

Cook decided not to publish his diaries ahead of last week's Labour conference in Bournemouth. Had he done so, his revelations would have ensured Blair received a much tougher ride from activists, many of whom are deeply uneasy about the war.

He reveals that in the months leading up to the war Downing Street aides, including Alastair Campbell, Blair's former director of communications, and Jonathan Powell, his chief of staff, were obsessed with not falling out with Washington.

Cook discloses that several cabinet ministers had held misgivings about the war, not just himself and Clare Short. At a cabinet meeting in late February 2002, Blunkett asked for a discussion on Iraq and Cook received cries of "hear, hear" from cabinet colleagues when he argued that Arab governments regarded Israel, not Iraq, as the real problem for the Middle East. Cook records it was "the nearest thing I've heard to a mutiny in cabinet".

His diary entry of March 7, 2002, a year before the war, says that Blunkett and Patricia Hewitt, the trade secretary, raised objections at cabinet.

"A momentous moment. A real discussion at cabinet. Tony permitted us to have the debate on Iraq which David [Blunkett] and I had asked for. For the first time that I can recall in five years, Tony was out on a limb."

According to Cook, Blunkett asked Blair: "What has changed that suddenly gives us the legal right to take military action that we didn't have a few months ago?"

Hewitt warned Blair: "We are in danger of being seen as close to President Bush, but without any influence over President Bush."

But the prime minister was "totally unfazed" and, when Hewitt again raised objections at cabinet the following month, Blair refused to be boxed in, telling colleagues: "The time to debate the legal base for our action should be when we take that action."

Cook reveals that Bush had wanted to hold a crucial war council with Blair in London on the weekend before the invasion of Iraq, a move that would have been a public relations disaster given public hostility to the war. Blair persuaded Bush to hold the summit in the Azores instead.

By September last year most of the cabinet had fallen into line. At cabinet on September 23, before parliament was recalled from its summer break, Cook says: "Personally I found it a grim meeting. Much of the two hours was taken up with a succession of loyalty oaths for Tony's line."

He says only Estelle Morris, then education secretary, "bravely" reported public disquiet that Britain was simply following Bush.

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