Blair knew that arguing Iraq would blot out his effort to discuss his programme for a third term. But his tongue was tied for other reasons as well. As the head of government, he could not speak of his disagreements with Bush. Out of loyalty to an ally, the national interest and protocol, he couldn't acknowledge that he had urged alternative policies on Bush. Blair never mentioned how he had wrung a commitment (honoured or not) out of Bush to restart the Middle East peace process. He did not discuss how the Bush administration had systematically ignored the British representative in Iraq, Jeremy Greenstock. He did not note that Downing Street was spitting blood over the depredations visited on it by the bullying John Bolton and the rest of the neoconservative cabal. He did not allude to his national security team's consternation over Condoleezza Rice's incompetence. He did not reveal the many ways he had supported Colin Powell in his struggles with Donald Rumsfeld and Dick Cheney. Blair's stalwart refusal to be transparent about his own good faith and positive actions contributed to his image as dishonest and furtive.

Blair's interlocutor within the Bush administration, Colin Powell, paralleled his quandary, and they were bonded, exploited and tarnished together. Of course, if Blair had not joined with Bush, he would have opened a large window of opportunity for the Tories. But, like Powell, Blair convinced himself that going along in public was essential to his efforts to influence Bush behind closed doors. Like Powell, every time Blair made a slight gain, he reinforced his delusion of influence. Both overvalued their leverage.

Blair knew that Bush had no practical post-invasion scenario, other than the neoconservative fantasy of a flower-strewn parade."There was little discussion in Washington of the aftermath after military action," according to a memo from Richard Dearlove, the head of MI6, to the prime minister on July 23 2002. After that, Powell presented the state department's 17-volume Future of Iraq prospectus, but was ruthlessly shoved aside; Blair, cornered, felt compelled to go to war without a plan. Thus regime change was botched from the start. It was a subject he could hardly discuss in the campaign. He was perpetually cornered.

British prime ministers have misjudged American presidents to their detriment before: Churchill and Roosevelt over the fate of the British empire, Eden and Eisenhower over Suez. The special relationship has been fraught with prime ministers intent on maintaining its veneer. Rumsfeld crudely drew attention to the inherently unbalanced nature of this alliance on the eve of the Iraq war, when he declared that British military forces were unnecessary -"there are workarounds".

In his relationship with Bush, Blair apparently misread the outward signs of American culture and interpreted them through British eyes. Bush can be so amiable and informal dressed in blue jeans that his manner can be mistaken for openness and cooperation, when it conceals a particular type of American class superiority and indifference. Bush, after all, seems so friendly compared with the glowering Cheney, who clawed his way upward. It's not easy for someone who's never travelled in America to grasp the evolution of the Bush family from north-east patricians into Texas Tories, and the dissolution of the New England character along the way, especially its sense of responsibility, duty and humility.

Bush's amiability towards Blair merely demonstrates his acceptance of the prime minister into his fraternity, his private club. But even if Blair got Bush exactly right in every nuance, the outcome remains the same. (Gordon Brown and Bush are a car crash waiting to happen. Bush has an instinctive revulsion for serious intellectuals who have little capacity for the locker-room banter that is his mode of condescension.)

The underlying events that produced this election result provide a harsh, cautionary and unsettling lesson not only for Blair. Prime ministers to come will take the story of Blair's embrace of a powerful ally's mendacity and Blair's subsequent loss of trust as a warning. Future American presidents will be regarded with underlying suspicion far into the future. By chastening Blair, the British voters have applied the only brake they have on Bush's foreign policy. But the damage done to the US-UK relationship could have incalculable long-term negative consequences for the world.