A ticking time bomb who threatens any truce

Cherie Blair has always been like the unexploded bomb that threatens every attempt to negotiate a lasting peace between the Prime Minister and his Chancellor.

A year ago, almost to the day, a radio journalist was surprised to be collared at a Labour conference by Mrs Blair, who described her No 11 neighbour as dysfunctional. She plainly did not want to see him take over her husband's job.

It was one of many private indiscretions that have fortified the suspicion that Mrs Blair has been encouraging the Prime Minister to hang on in office, and hoping that someone more to the Blairs' taste would emerge as a credible alternative to Gordon Brown.

Yesterday's indiscretion was different only in that she uttered the words in front of a witness who was prepared to repeat them publicly. But still the damage could have been undone if Mrs Blair had gone in front of a camera immediately, rather than waiting several hours. After agonised negotiation between advisers, a press officer who works with the Blairs pointed out the problem of confronting the press. "Could she do that? Whether she said those words or not, they're so obviously what she thinks. So she goes in front of the cameras and someone asks 'Do you actually like Gordon Brown?' ­ what is she going to say?"

In the bars and restaurants delegates' opinions were divided over the issue last night, with many blaming the media for exacerbating party divisions. Mrs Blair eventually issued a denial, emerging just after 7.30pm to insist: "Honestly guys, I hate to spoil your story, but I didn't say it and I don't believe it either."

Senior figures rolled out to defend her conduct. Lord Kinnock said: " That's not the Cherie Booth I know and I've known her since she was a little girl," while Tessa Jowell, the Culture Secretary, said the report was "complete and utter rubbish".

Supporters of Mr Brown attempted to draw a line under the incident, despite clear irritation that the speech in which he set out his leadership credentials had been overshadowed.

But Stephanie Booth, Mrs Blair's step-mother, stoked the fires last night when she told Newsnight that her step-daughter is "not [Mr Brown's] biggest fan". Her father, Tony Booth, added: "Who is?"

The feud goes back some 14 years. After Labour's 1992 general election defeat, Mr Blair floated the idea that Mr Brown should run for the party leadership against John Smith, while Mr Blair himself was thinking of running for the deputy's post.

Mr Brown talked him out of it, apparently out of loyalty to Mr Smith. But Mrs Blair suspected Mr Brown had selfish motives. She suspected that he feared an outcome in which he lost to Mr Smith, but Mr Blair won the race for deputy. Even then, Mr Brown was enough of a family friend to be a guest at Mrs Blair's 40th birthday party, in September 1994.

In mid-2004, Mr Brown's allies believed he had a copper-bottomed promise from Mr Blair that he would resign that year. There was even public confirmation, in September, when Melvyn Bragg, whose wife Cate Haste had been co-writing a book with Mrs Blair, said publicly that the Prime Minister had been on the point of quitting. The Braggs had been guests at Cherie's 50th birthday party at Chequers ­ to which the Browns were notably not invited.

But those who thought they had succeeded in levering Mr Blair out of No 10 reckoned without his wife, who came out publicly to flatten the notion. "There never was a moment when he was going to resign," she said on Channel 4. "I can assure you if he had done, I would have known."