Tony Blair memoirs: Blackmail and skulduggery at the heart of government
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The former prime minister devoted much of his book - A Journey - to the fraught relationship he had with his chancellor and successor in No 10.
He said it was so difficult that it led to him turning to drink.
The strength of the allegations led former deputy prime minister John Prescott to warn that the book could potentially spark a civil war in the Labour Party.
Mr Blair claimed Mr Brown was at times "strong, capable and brilliant", but also "maddening".
In a BBC interview with presenter Andrew Marr broadcast last night, he added that people had "overestimated" Mr Brown's capacity to be prime minister.
He said the pair's relationship had been "hard, going on impossible" at times, and he claimed Mr Brown had "backed away" from New Labour principles that could possibly have secured an election win in May this year. However, he insisted it was a myth that he had ceded power on economic issues to Mr Brown as part of the famous deal to make him Labour leader. He said he had kept "close control" of economic issues, and that the suggestion had come because of a paper produced by Peter Mandelson when he was brokering a deal between the two men.
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Mr Blair suggested that, even when he had been a devoted follower of Mr Brown's in the 1980s, when the Fife MP was seen as the one who would one day be Labour leader, he noticed his future chancellor would prefer to "reframe the questions" rather than "come up with hard answers."
He went on: "The relationship with Gordon was very, very difficult; it was also very close.
"Even though, towards the end, frankly, it was hard, going on impossible, for a large part of the time we were in government, he was an immense source of strength.His contribution to the successes of the Labour government was clear."
Turning to his successor's term in office, Mr Blair said: "I always knew that if we departed a millimetre from New Labour, we were going to be in trouble.
"In my view, what we needed to do in 2007 was we needed to renew New Labour with vigour, take it to the next stage, being the party that reforms welfare and public services, carried on deepening those reforms.
"I think we somewhat backed away on them."
But the most explosive revelation centred around the "cash for honours" allegations, when Western Isles SNP MP Angus MacNeil reported Mr Blair to the police.
In his memoirs, Mr Blair described a meeting about pension reform involving him, Mr Brown and work and pensions secretary John Hutton.
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Mr Brown, who disagreed with the other two men on the issue, came in and, according to Mr Blair, threatened to have an internal Labour Party inquiry on the "cash for honours" affair if he did not get his way.
Mr Blair then suggested that Mr Brown had been behind an intervention by Jack Dromey, then party treasurer and husband of Harriet Harman, who called for an inquiry, claiming he knew nothing of the secret loans allegedly connected to the awarding of honours.
It is not the book's only suggestion of skulduggery on Mr Brown's part. In an earlier chapter, Mr Blair implied that Mr Brown had attempted to frame him in the run-up to John Smith becoming leader, by pretending to consider standing in the leadership race himself so that Mr Blair would declare against Mr Smith.
Lord Prescott, who often acted as a go-between during rows between the two men, said the memoirs presented only a "one-sided version" of their relationship. He rejected the suggestion that Mr Brown had dumped the New Labour agenda, arguing: "I hear Tony say we didn't continue with New Labour policies … Gordon continued these policies. He didn't disown them."
He warned it would be "very, very damaging" for the party if the "wars" between Blairites and Brownites continued and the leadership candidates refused to serve under one another.
"We have a fight now between 'Is it left, is it right, is it New, is it Labour?' Forget all that. Let's all be Labour and get behind the new leader," the former deputy prime minister said.
Mr Brown last night remained silent over the attacks on him by his former friend, colleague and rival, but SNP MP Mr MacNeil called for him to make a statement.
He said: "Gordon Brown must respond to these extraordinary accusations that he, in effect, tried to blackmail Tony Blair over the cash-for-honours scandal in a clash about pensions reform.
"What did Gordon Brown know about the scandal that meant he could use the threat of an investigation as some kind of leverage over Tony Blair?
"The whole think stinks, and it seems the full truth about Labour's cash-for-honours scandal is still to be fully unravelled."