Blair signs book deal 'worth £6m' - and he hasn't written a word yet

The former prime minister is expected to spare few details of his turbulent relationship with Gordon Brown.

The publisher, Random House, refused to put a figure on the deal. But experts say it could earn Mr Blair as much as £6million.

A large advance would help the Blairs with the crippling £16,000-a-month mortgage payments on their Connaught Square home.

Friends of the ex-premier said he had "not even started writing yet" so publication was at least two years away.

This means it may not come out until after Mr Brown fights the next General Election, which would give his predecessor more leeway to write what he likes.

The book will be published as a single volume but there will also be lucrative serialisation rights in the UK and the U.S.

Mr Blair, who took up a job as Middle East envoy after quitting No 10 in June, said last night: "I hope my memoirs will provide a serious and thoughtful, but also entertaining, reflection on my time as a Member of Parliament and as Prime Minister."

The book will be published under the Hutchinson imprint in Britain and by Alfred A Knopf in the U.S., both part of the Random House group.

The publisher beat Rupert Murdoch's company Harper Collins in a bidding war for Mr Blair's signature.

The chief executive of Random House is Gail Rebuck, who is married to Lord Gould, Mr Blair's senior pollster during his time as Labour leader.

Miss Rebuck said: "We are absolutely delighted to be publishing Tony Blair's memoirs.

"He was an extraordinary prime minister, and this will be an extraordinary book.

"It is a great privilege for all of us to be working with him on this unique project."

Mr Blair had used the same agent who negotiated Bill Clinton's publishing deal.

Washington lawyer Robert Barnett secured a massive £6million for the former president's autobiography My Life and, with a joint UK and U.S. deal, Mr Blair could expect to match that figure.

His wife Cherie has already earned a reputed £1.5million for her life story, to be published next year.

She is also rumoured to be dishing the dirt on her husband's relationship with Mr Brown.

Leaving number 10 has allowed Tony Blair time to take to the lecture circuit, where it is believed he will earn anything up to £100,000 a night.

Cherie Blair has already appeared on the professional lecture circuit, reportedly charging £100,000 for a tour of Australia and £30,000 for a single event in the US.

Tony Blair's current job as Middle East Peace Envoy is unpaid, although it does come with office expenses of around £100,000.