The wholly unexpected move was the boldest by a Labour leader since Hugh Gaitskell's abortive attempt to do the same in 1959. It is the most potent symbol of the party's transformation into what Mr Blair yesterday called a 'modern party living in an age of change'.
The momentous implications of his decision, which was one of the most closely guarded secrets of recent political history, to end a generation-old taboo by reopening the issue of the party's 'objects and objectives' was still sinking in as delegates rose to give Mr Blair a spontaneous ovation of more than six minutes. The party leader left the revelation that he and his deputy, John Prescott, would be drawing up a new section of the constitution to the very end of a confident and rapturously received hour-long speech setting out his vision of a modernised Labour Party as the 'mainstream voice in politics today. . . the party of the majority'.
Mr Blair's determination to exceed even the expectations of some of his closest allies in pushing forward change in the party was underpinned last night by the disclosure that he and Mr Prescott will produce a draft statement by December for the party's national executive. After a lengthy period of debate the party will be asked to approve the new constitution at next year's conference.
The traditionalist far left of the party, spearheaded by an angry Arthur Scargill, the miners' president, and Dennis Skinner, newly re-elected as an executive member, yesterday immediately announced a ferocious campaign to keep the clause. Mr Scargill said Mr Blair had 'declared war' on the party's constitution, while Mr Skinner claimed that there were thousands of Labour Party members ready to resist 'dumping Clause IV.'
There was every sign last night, however, that Mr Blair will succeed where Gaitskell failed. Although there were some private rumblings from the centre-left of the Shadow Cabinet, the senior union leaders who still command 70 per cent of the party conference votes refused to condemn the plan to redraft the party's objects. Other Labour figures were openly delighted, comparing Mr Blair's announcement with the historic Bad Godesburg conference of 1959 at which the German SPD broke with its Marxist past.
Mr Blair was said last night to be settled in his view that the ancient clause, drawn up by Sidney and Beatrice Webb, which summarises the purpose of the party and declares in its fourth paragraph that it seeks 'the best obtainable system of popular administration and control of each industry and service', was an 'inadequate and narrow' view of the objectives of a modern socialist party. Although there will be intense discussion between senior party figures between now and Christmas, the statement of aims is likely to include a commitment to 'economic efficiency and social justice'. He told the conference the party required 'a modern constitution that says what we are in terms the public cannot misunderstand and the Tories cannot misrepresent'.
Mr Prescott was brought into discussions several weeks ago when Mr Blair first decided to replace the clause. But several of the party's most senior figures and union leaders were not let into the secret until the last days, or in some cases, hours before the speech. The normal texts were not issued to the press.
In an eloquent, skilfully crafted and faultlessly delivered speech, Mr Blair had already prepared the ground for overcoming resistance to his dramatic final announcement. As well as going out of his way to make a ringing commitment to the continued public ownership of the Post Office and British Rail, he won warm applause by declaring that 'we should stop apologising for the word socialism'.
He added: 'It is not the socialism of Marx or state control. It is rooted in a straightforward view of society. It is our understanding that the individual does best in a strong and decent community of people with principles and standards and common aims and values. We are the party of the individual because we are the party of the community.'
While using little of the language of Labour's old-time religion, Mr Blair delighted delegates with an excoriating attack on the Tories' record, combining a robust defence of his belief in individual responsibility with a sustained and sarcastic attack on the Tories' failure to contain crime and 'sleaze' while fostering a 'power elite of money shifters, middlemen and speculators'.
And projecting 'New Labour' as the real party of the family, Mr Blair declared that the Tories were 'no more the party of the family than they are the party of law and order'.
Reasserting the Labour Party's radicalism, he highlighted educational standards and constitutional reform among his key objectives for government and for the first time declared his unequivocal support for the proposed new voluntary national task force aimed at giving a new sense of purpose to the 'nearly one million young people in this country who have no work, training or education'.
At the same time he underpinned Labour's determination to reform the welfare state - on which the Social Justice Commission's recommendations will be published on 24 October - saying: 'We are the only people who can be trusted to change it, because we are the people who believe in it.'
Blackpool reports, pages 6, 7
Leading article, page 13
Mrs Blair's flair, page 18