So, it truly is an end of era. Mr Blair, 13 yrs ago swept into Downing Street after dawn, Mr Brown swept out of Downing Street, just before dusk.
Many commentators would say, Blair's performance as premier, outshone his predecessor, Brown. But history judges individuals in context. Mr Blair was a natural leader, but held No 10 in easier times. His successor did better with a tough hand.
The Labour Prime Minister, Brown most resembles is James Callaghan. Both arrived at No 10 after a long wait, succeeding younger, more charismatic men. Neither secured a personal mandate from a General Election. Both premierships were dominated by severe financial crises. Each man was far more in tune with the Labour movement and trade unions than their predecessors, and both were moved by a moral purpose.
They arrived with substantial reputations, both declined early elections that they might well have won, an option available to Brown which – unwisely, with hindsight – he chose not to take up.
By 2007, Gordon Brown faced a country growing tired of Labour, the revival of the Tories under David Cameron, and a disillusioned press. He then encountered the worst economic catastrophe since the depression and then the expenses crisis.
Although still many celebrate Labour's substantial achievements, these were the economic and welfare advances in Blair's first term, which incidentally were principally those of Brown, much the more creative force in those four years, while the constitutional reforms were the legacy of John Smith and Neil Kinnock.
On the whole Britain by 2010 has certainly become a more compassionate, open and fairer society.
It was Brown's serendipity that the economic crisis that will colour his entire premiership played to his strengths. His handling of it domestically and abroad will receive far more praise than criticism.
History will show that Brown achieved more in Northern Ireland, on foreign policy, including deterring India's fury against Pakistan after the Mumbai attacks in 2008, and protecting the most vulnerable, than he was given credit for.
The manner of his exit still earned him respect and sympathy, and these are the tints with which his legacy will be painted; not the greatest prime minister, but a man of deep intellect and passion whose ambition and temperament often got the better of him, but who served his country with honour and good judgment at a time of grave national crisis.
It's the fighters and believers who change our world, Gordon Brown was both.
UPDATE : The Guardian have released photos of Gordon Brown's last hours in Downing Street, showing him with his family and closest aides, and saying goodbye to his staff, as the rest of the country was waiting to see weather he would resign or not.
They are truly emotional pictures, showing Gordon a family man to the end, showing the last moments of 13 years of a Labour Governement and they also show who Gordon Brown's inner circle really was; Lord Mandelson, Ed Balls, Ed Milliband, Douglas Alexander, Alastair Campbell, Justyn Forsyth, Stuart Wood and Gavin Kelly.