The relationship between Tony Blair and Gordon Brown his chancellor has come under the spotlight in a number of political books in recent years. Here are some which have alleged tensions at the top.
GORDON BROWN, BY PAUL ROUTLEDGE (1998)
The book claimed the chancellor was convinced Mr Blair had broken a secret pact forged between the two during the 1994 Labour leadership election.
Mr Brown denied authorising his book but his ally, then Chief Whip Nick Brown, was named as a source by Routledge.
The biography unleashed a media storm while the prime minister was visiting Japan.
In the wake of its publication, Observer journalist Andrew Rawnsley quoted somebody very close to Mr Blair saying it was time Mr Brown got to grips with his "psychological flaws".
SERVANTS OF THE PEOPLE, BY ANDREW RAWNSLEY (2000)
Rawnsley's "inside story" of New Labour detailed more rows between the neighbours in Downing Street.
It reported that when Mr Blair promised to bring British health spending up to European average levels, the chancellor roared at him: "You've stolen my f****** Budget!"
The book also provoked controversy by saying Mr Brown had told aides he had lied when asked on Radio 4 about Formula 1 boss Bernie Ecclestone's donation to Labour - something the chancellor denied.
It also went into tensions between Mr Brown and Peter Mandelson and his falling out with then Bank of England governor Eddie George.
THE RIVALS, BY JAMES NAUGHTIE (2001)
The BBC Today programme presenter's account of the Blair-Brown "marriage" is said to have been widely used for a Channel 4 dramatisation of the relationship.
It said the prime minister privately had flatly denied ever promising to stand down in favour of Mr Brown and was set on continuing in Number 10 for a third term.
The book also claimed Mr Brown was so frustrated about his prospects that he had considered taking jobs in the International Monetary Fund or European Central Bank.
OFF WHITEHALL, BY DEREK SCOTT (2004)
Former Downing Street economics adviser Derek Scott used his book to brand Mr Brown "obstructive and deceitful".
He suggested Mr Brown was reluctant to discuss policies beyond his close circle of aides once his mind was made up and left No 10 in the dark.
When Mr Blair asked about the 1998 Budget, Mr Brown replied: "I haven't made my mind up." Mr Blair countered by saying: "Give me a hint, Gordon."
AN HONOURABLE DECEPTION, BY CLARE SHORT (2004)
The ex-international development secretary's published diaries said she had acted as a go-between between Mr Blair and Mr Brown.
And she claimed the prime minister had offered to stand down before the next general election if the chancellor agreed to back plans for the UK to adopt the euro.
"Gordon's answer was, firstly, that such deals were not worth talking about because previous agreements had not been kept, and, secondly, he would not contemplate recommending that we join the euro in order to advance his own position rather than advance the economic interest of the country," she wrote.
GORDON BROWN, BY TOM BOWER (2004)
Yet more claims of rifts between Mr Blair and Mr Brown during the 1994 leadership contest came with this critical biography.
Bower quotes Voltaire to describe Mr Brown in these terms: "He loves mankind; therefore he does not need to love his neighbour."
BROWN'S BRITAIN, BY ROBERT PESTON (2005)
The latest tome says the two men have "mutual animosity and contempt".
It claims Mr Blair decided in November 2003 he would quit because he felt he had lost voters' trust because of the Iraq war.
He had then changed his mind in June 2004, following intervention from Cabinet allies and suspicion that the chancellor was manoeuvring against him.
It quotes Mr Brown telling the prime minister at one point: "There is nothing you could ever say to me now that I could ever believe."