Police poised to charge Blair's top adviser
Publisher: Jon Land
Blair's 10-year reign to end 'within weeks' (Pic: PA)
Tony Blair's decade at 10 Downing Street marks him out as one of those rare politicians who put their stamp on an era.
But no sooner has that milestone been passed than the Blair era will come to an end, with the Prime Minister's resignation expected within weeks, or even days.
There is almost universal agreement that Mr Blair's successor will be Chancellor Gordon Brown. But the apparent inevitability of this long-awaited transition masks a considerable degree of uncertainty about the era to come.
Will a Brown premiership mark a radical break from the Blair administration? Or will the man who insists he was as much a progenitor as the PM of the New Labour project preside over a period of continuity?
Will Mr Brown embark on a purge of Mr Blair's ministers and policies?
And, perhaps most importantly, how long will the Brown era last?
Conservatives have been busy over the last few years predicting that Brown will swing Labour to the left, ushering in a period of business-unfriendly, bureaucratic centralisation.
But Mr Brown himself has been equally busy sending out signals that he will not be a creature of the left, voicing his support for nuclear power and the renewal of Britain's independent nuclear deterrent as well as loudly trumpeting his patriotism with calls for a Britishness day and pride in the flag.
No-one doubts that Mr Brown is planning to hit the ground running with 100 days of eye-catching policy announcements to match the declaration of independence for the Bank of England he made within days of becoming Chancellor.
Only a few in the Chancellor's inner circle know what those announcements will involve. Speculation revolves around the creation of a written constitution, a timetable for withdrawal from Iraq, NHS independence, scrapping ID cards or a Whitehall shake-up including the abolition of the Department of Trade and Industry.
He is expected to reward key allies with top Cabinet posts, with Alistair Darling tipped to succeed him at the Treasury, promotions for Ed Balls, Douglas Alexander and Ed Miliband and a senior position for his campaign manager Jack Straw.
But it remains to be seen whether he clears out ministers too closely linked with the Blairite past. David Miliband, who has ruled out a challenge for the top job, will almost certainly survive as a signal that Mr Brown wants to lead a "Cabinet of all the talents", but there are doubts over the future of close Blair allies like John Reid or Tessa Jowell.
Mr Brown will also have to decide whether to appoint the victor of the deputy leadership race to be his Deputy Prime Minister.
Although the deputy's contest is seen as a chance for Labour's grassroots and the unions to influence the shape of a Brown premiership, there is no requirement for the winner to become DPM, or indeed for the post to be filled at all.
Left-wing candidate Jon Cruddas has said he does not want the DPM job, and there are others who Mr Brown would probably prefer not to see standing in for him during his holidays. Mr Prescott's old job could even go to Mr Straw if he is not sent to the Treasury or Foreign Office.
Whatever the personnel of his Cabinet, Mr Brown faces an enormously more difficult economic and political climate than Mr Blair did when he arrived at Downing Street on a wave of euphoria in 1997.
He will take office against the backdrop of possible charges in the cash-for-honours inquiry, rising inflation threatening to force up interest rates and no end in sight to the violence in Iraq.
Rather than representing a clean break after years of Tory rule, as Mr Blair did, Mr Brown faces the far more daunting challenge of winning back voters disillusioned by a decade of Labour.
And in place of the deeply unpopular John Major, he will face Tory leader David Cameron buoyed by months of comfortable opinion poll leads - with surveys suggesting the gap in the Conservatives' favour may even widen when Mr Brown takes over.
After one of the longest waits for power ever seen, Mr Brown knows he has his work cut out if he is not to enjoy one of the shortest periods in power in British political history.
Despite some speculation over a snap election in 2008, he will almost certainly wait until 2009 or 2010 to give himself time to turn the polls round and maximise his chances of winning a fourth election victory for Labour.
The actual process by which Mr Brown - or, just conceivably, someone else - becomes Prime Minister has been set out by Labour's ruling National Executive Committee.
Mr Blair's announcement of his resignation - accompanied by that of his deputy John Prescott - will not mean the immediate arrival of removal vans in Downing Street.
The NEC will meet within 72 hours to finalise a timetable for seven-week contests for the leadership and deputy leadership, and would-be candidates will then have a week to file nomination papers bearing the signatures of 12.5% of Labour MPs - 45 names, including their own.
Mr Brown will have no difficulty in clearing the nomination hurdle, but his two declared rivals - left-wing MPs John McDonnell and Michael Meacher - will struggle to do so.
Even if they get onto the ballot paper, neither man will present any threat to the Chancellor's elevation. Indeed, he would probably welcome their candidacy as a chance to demonstrate his mainstream credentials.
The prospects of a challenge from the "Blairite" centre seem to have receded in recent weeks, with Mr Miliband saying he will vote for Brown and problems at the Home Office making a leadership bid by Mr Reid less credible. Long-shot Blairite candidates Charles Clarke and Alan Milburn have not ruled out running in order to ensure the Chancellor is not anointed unopposed.
If the leadership is contested, the winner will have to secure more than 50% of Labour's electoral college, which is divided three ways between 380 MPs and MEPs, 200,000 party members and 3.2 million trade union affiliates.
Even without a rival, the NEC's rules require Mr Brown to attend hustings alongside the deputy leadership candidates before finally taking the crown he has waited a decade for.
But he will not have to face an "affirmative vote" in the absence of a challenger, as some Labour figures demanded.
The new leader - and deputy leader - will be announced at a weekend meeting of representatives of each section of the electoral college, probably in late June or early July.
Candidates so far declared for the deputy leadership are Hilary Benn, Hazel Blears, Jon Cruddas, Peter Hain, Harriet Harman and Alan Johnson.