It has long been known that Mr Blair had previously agreed that he would not stand against Mr Brown, and that Mr Blair was persuaded after the premature death of John Smith that he must renege on that pact because, in the view of his supporters, he would make a better leader.
But the fact that Mr Brown and his allies still nurture their grievance over the issue three years later, after Labour's landslide victory and Mr Brown's appointment as Chancellor of the Exchequer, yesterday delighted his many party critics.
Evidence that the sore still festers is provided in a new biography of the Chancellor, extracts of which began to leak on Wednesday.
Paul Routledge, the political correspondent of the Independent on Sunday, whose biography is to be published shortly, says in the book: "Privately, Brown's friends believe Blair let him down, and there can be little doubt that they represent his feelings accurately. Blair repeatedly promised Brown he would not stand against him in a leadership election."
One ministerial source said Mr Brown's "overpowering ego" would eventually prove his undoing, as it had proved the undoing of Denis Healey and Nigel Lawson before him.
The difference with Mr Healey, if the impending biography of the Chancellor is to be believed, is that Mr Brown has a strong powerbase within the party - something that could yet ensure his succession to Mr Blair.
The first edited extract from the biography, published in today's Times, sells Mr Brown's decision to step aside from Mr Blair as an act of supreme self-sacrifice, "of doing ones duty to the party." Mr Routledge, who is a long-standing friend of Charlie Whelan, the Chancellor's trusted media man - says in the book : "Some anti-Brown campaigners were insinuating allegations about his private life. They also completely distorted Blair's previous promise to Brown that he would not stand against him. In the end, Brown felt he had to make a choice between his own leadership claims and the needs of the party. A damaging contest would help no one. He would support Blair.
"There was no overt `deal' between the two, only a recognition on Brown's part that while he would win, the contest would damage Labour's chances for the future." The book suggests that the quid pro quo was a pledge by Mr Blair to consolidate Mr Brown's position as shadow chancellor - and then chancellor.
"He would have full charge of economic policy and a powerful influence across the range of social policy."
Some of Mr Brown's party opponents - a band that has been increased by the threats he is said to be instigating against welfare benefits for the disabled and other vulnerable groups - have noted that he continues to cultivate support.
One ministerial source said that he had held a Christmas party at Number 11 for Labour Party constituency secretaries, and he is said to be assiduous in maintaining an alternative power-base within the party at large.Reuse content