Mr Blair expressed full confidence in Mr Cook, describing him yesterday as "probably one of the most respected foreign ministers in the rest of Europe that Britain has had for years and years and years". Warning against adopting Hollywood-style obsessions with politicians' private lives as seen in the US, Mr Blair said on BBC's Breakfast with Frost: "We can either have the news agenda dominated by scandal and gossip and trivia, or we can have it dominated by things that really matter."
He also remained enthusiastic about closer links with the Liberal Democrats, in spite of a threat of confrontation with some cabinet ministers who want an early referendum on proportional representation to call an end to the relationship.
Mr Blair refused to rule out bringing back Peter Mandelson to the Cabinet, although the objections of senior colleagues are likely to make it impossible until after the next election.
Mr Blair alarmed colleagues by saying there were few ideological differences with some Liberal Democrats, and the controversy over Mr Cook may prove a sideshow in the power struggle within the Cabinet.
In her book, serialised in The Sunday Times, Margaret Cook exacts bitter revenge on her ex-husband, who left her to marry his secretary, Gaynor Regan.
She alleges that he had at least six affairs during their 28-year marriage. More damagingly, she points out personal rifts within the Cabinet. She reveals that her former husband "hated" Mr Mandelson, and that there was bad blood between Mr Cook and Gordon Brown that began when they took opposing sides in the Scottish devolution debate. She also recounts that Mr Blair's ditching of Clause IV of the party constitution "gave Robin digestive problems". She says he admitted he had "sold his soul" to New Labour for high office.
However, the accounts of his sexual adventures, which he confessed to his wife on a weekend in the Lake District, were not seen last night as a sackable offence. Mr Blair has said he would not tolerate sleaze such as financial impropriety among ministers, but he has told friends he will not sack ministers for sexual affairs and marriage breakdowns. "He has been a rat but not a crook," said a source close to Mr Cook.
As Labour MPs rallied round Mr Cook yesterday, one ministerial source said: "Anyone who had six affairs in the last 30 years would not get into the fourth division of European adulterers ... and it will have zero impact in the American administration with Clinton's background."
Female Labour MPs turned against Mrs Cook. "She appears to have gone from victim to vixen and I don't think that does her any good and I don't think it does women any good either," said Bridget Prentice, an assistant government whip.
The timing may also be fortunate for Mr Cook, with Mr Mandelson - who wanted his job as foreign secretary - out of the way, and the Government fighting this week to get back to the New Labour modernising agenda, with announcements on education, law and order, and welfare reform.
Mr Cook spoke to Mr Blair on Saturday on the Blairs' return from Kuwait, to agree a media strategy to deal with the book's publication. Mr Cook had also prepared the ground by holding a dinner with Mr Mandelson to discuss the handling of the media over the book, and had a meeting at the Treasury with Mr Brown to clear the air over their past rivalries.
Mr Cook spent the weekend at his official residence, refusing to be drawn on the detailed allegations, but he authorised a member of his staff to reject the claims by his ex-wife that he had a drink problem: "He is not going to be hitting back at Margaret, but anyone who worked with him would know that he did not have a drink problem."
The Foreign Secretary will this week join in a media blitz organised by Downing Street to reaffirm the New Labour agenda, in spite of the loss of Mr Mandelson, one of its principal architects.Reuse content