It was an "in" joke, because it only meant something to party members aware of the sensitivity of suggestions that "Labour" was an out-of-date concept, which were made at the time of Hugh Gaitskell's doomed attempt to rewrite Clause IV in 1959. The subtext was clear: "I could change the name if I wanted to, but I have decided not to do so at this time. Besides, I have already changed the name to New Labour without consulting you." It smacked of a disdain for the party he led, and John Prescott looked unamused, although - an intriguing detail, this - it had been "cleared" with him in advance.
The Clause IV vote marked the end of the first, triumphant phase of Blair's leadership, a nine-month honeymoon with both party and electorate. But since then the colour of Blair's leadership has darkened: it is still moderately dazzling, but perceptibly less so than before. Something deep and significant is going on: the weaknesses of a Labour government are becoming clearer.
The extraordinary thing was how few errors Blair had made until last December, when Harriet Harman, one of the few Labour MPs who could be described as a personal friend, told him that her son had passed the exam to get into a selective grammar school. Blair's misjudgment was obvious in retrospect: he did nothing. The famed New Labour media management machine failed to minimise the damage caused when the decision became known - at a time of the Mail on Sunday's choosing - the following month. This was partly because Alastair Campbell, the leader's press secretary, was personally deeply opposed to Harman's decision, which in itself ought to have warned Blair that he had misjudged the mood of the party.
The cause of comprehensive education is totemic in the Labour Party, with the issue of selection at the top of the totem pole. But even after the fuss about his own son's school - in which Roy Hattersley was reborn as a left-wing firebrand - Blair could not see it.
What could he have done? The news could have been released over Christmas instead of when MPs were at Westminster, and Harman could have given a personal interview to say what she told friends at the time: "It's easier to go through the eye of a needle than be a good mother and a good politician."
Above all, they needed to work out an explanation for what she had done that could be communicated to the party and the people. Even now, the argument in defence of Blair and Harman's schooling decisions is flawed. Only yesterday in his Mirror interview, Blair repeated that he would not "sacrifice" his child to avoid a political row - implying that parents who do not choose the London Oratory are taking their children to the top of the nearest hill and cutting their hearts out.
The Harman affair confused Labour's message on education, and crystallised a certain unease voters felt about the slick new Labour Party - they "say one thing and do another". And the affair became entangled in the second important mistake of Blair's leadership. Harman had been forced to go public two days after Labour MPs had clashed at their weekly meeting over the idea of abolishing this year's Shadow Cabinet elections.
Blair thought they were an unnecessary distraction, but once more failed to act early enough, again partly because he misjudged the mood of the party. It was not until the summer that he was finally forced to admit defeat and instead agreed to the next best option of bringing the elections forward from their usual November slot.
Thus Labour MPs who wanted to be helpful to their new leader and his rather unfamiliar "project", even if they were not very good at it, found themselves forced to vote for the "leadership slate" of the existing team - or for a bunch of no-hopers. This they did not like, but Blair might just have got away with it if he had not then compounded it with two further mistakes. First, his spokespeople told journalists that the leader was displeased with "wild" allegations of arm-twisting and vote-rigging and that there would be a review of the disciplinary rules for Labour MPs. Then Clare Short was demoted.
The first was unnecessary escalation, which spoke of Blair's genuine frustration with the more outlandish claims made by Ken Livingstone and Ann Clwyd. The elections were hardly "free and fair", but there were no ballot boxes stuffed with bundles of papers in the same hand.
The second sent shock waves through the wider party. Clare Short had not been tactful, and she had not made a stunning success of her transport brief. But for all her Sunday morning television interviews, which sent the doctors into a spin over tax or cannabis, Short was transparently a speak-your-mind politician who wanted Blair to win and to be part of New Labour, however alien it was to her kind of socialism.
It is unusual for the victim of an error to see clearly the lesson of their misfortune. But Short went to the heart of the problem when she said that the message of her exile was to ask people to vote for New Labour on the basis that some of the people in it were nothing to do with the "absolutely appalling" old Labour Party. Still, it would have been better to keep Short on board so that she, as well as John Prescott, could embody the conversion of old Labour to new.
Since the Clause IV victory, Blair has said less about his distinctive views of morality, family and crime, and his language has become more artificial, with more of the inevitable evasions of political office. As a result people have paid less attention to what he has been saying, and other messages have become important: that he did not send his child to the local school; that his wife is an ambitious barrister who earns a lot of money; that his party squabbles.
And the obsession with being a "tough" leader is beginning to become counter-productive. Short's own demotion was the prime example: it begged the question, what was her crime? Calling for a debate on the legalisation of cannabis and saying that people on her level of income should pay more tax? A larger and more confident leader would have said that was just Clare thinking aloud, it is not the policy of the party. As a result, it was an act of discipline which spoke of weakness rather than strength.
There have been other mistakes, all illuminating the same weaknesses. Even before Labour MPs were asked to take part in a meaningless re-election of the entire Shadow Cabinet, it emerged that Labour members would be asked to take part in a meaningless ballot on the contents of the draft manifesto. Before the manifesto, New Life for Britain, was published, journalists were told that there would be a process of "consultation" over the summer, before it is put to the vote at conference on Thursday and then to a referendum of all party members later next month.
It emerged that this meant consultation in the sense that Clare Short was consulted about her new post. The document that was published on 4 July is the document members will vote on. The ballot paper will not offer a choice between "Yes, I would like to win the next election" and "No, I would prefer to stay in opposition", but it might as well. It is a cosmetic exercise designed to demonstrate that the party is united behind the leadership's programme and thus largely ineffective. The party, rather than being inspired, is sullen.
Then there was Shadow Chancellor Gordon Brown's announcement in April that he wanted to abolish child benefit for those aged 16-18 and replace it with payments to those who need them to encourage young people to stay on at school or college. The second part of that sentence was hardly noticed. While Brown himself trumpeted this as evidence that he was prepared to take "tough decisions" about the welfare state, it was not clear until earlier this month that he was talking more about facing the Labour Party with the need to reconsider the sacred principle of universal benefits than facing the electorate with the need to provide for themselves.
And finally there was the mishandling of the referendum on a Scottish parliament. The main problem was that the news leaked in London rather than being announced in Scotland, as planned, but there was a devil-may- care boisterousness about Blair's defence of his policy afterwards which helped to annoy Scottish opinion even further.
Of course, Blair's response to these criticisms, especially the last one, is to say, Very well, but is what we are proposing right? And the answer, in cases of policy, is yes. The present system of child benefit for the older age group is anomalous, although it is a relatively minor anomaly, because teenagers who leave school do not get it. And a referendum in Scotland is right in principle and necessary to get the legislation through the Commons.
But the real question is how the changes are handled. The contrast between the mistakes of this year and Clause IV is telling. On Clause IV, Blair took to the road and argued his case directly with party members. Many of them did not like it, but his argument was better, and they had to accept it. But the debate on Clause IV was a genuine, and genuinely dangerous, one, unlike the passive approval demanded for the manifesto.
After the excitements of creating a new party within the shell of the old, Blair has been revealed for what he always was - a politician, albeit a striking, youthful, articulate and clever one. Part of this was inevitable, as his newness and image as a "normal person", rather than a politician, wore off. But part of it was an unnecessary squandering of what was so valuable about him when he was elected: that he spoke in a different language.
If Blair's mistakes have a theme, it is that they all speak of a failure to try to take people with him - a political virtue of which he has often spoken. This is not just the "old Labour" complaint about centralisation and needless provocation of the party, because it applies beyond the party too. The case for a Scottish referendum and for changes to child benefit seem insufficiently related to Blair's message to the country.
The paradox is that it is Blair who spoke of Margaret Thatcher as coming to confuse knowing her own mind with refusing to listen. When he became Labour leader, he made some large claims to a new politics, to a new language of moral community, to "say what we mean and mean what we say". These claims have been weakened this year. His task this week is to renew them.
The revised paperback edition of `Tony Blair', by John Rentoul, is published by Warner Books, pounds 16.99.Reuse content