His voice cracking with emotion and close to tears, Mr Brown told the nation it had been a ‘privilege to serve’ and do a job he loved, bringing to an end his Premiership which had lasted two years, ten months and 14 days.
For the first time ever, his children John, six, and Fraser, three, appeared beside him in public and the family posed together in touching scenes before walking away hand-in-hand.
And Mr Brown paid tribute to his wife’s ‘unwavering support and her love’ and to his sons ‘for the love they bring to our lives’.
After telephoning his predecessor Tony Blair, Mr Brown resigned with immediate effect as Labour leader and Prime Minister, leaving Harriet Harman as acting leader of the opposition.
Last night he and his family flew to Scotland after departing from Number Ten for the last time.
A plot orchestrated by an unelected cabal around Mr Brown to try to prop up Labour despite its election defeat was crushed by a revolt led by senior Cabinet ministers, who argued it would be undemocratic.
Lord Mandelson and Tony Blair’s former spin chief Alastair Campbell were facing a fierce backlash from colleagues for persuading Mr Brown to make an ‘undignified’ offer on Monday to stay on until the autumn before quitting in an attempt to lure the Lib Dems into a power-sharing pact with Labour.
Instead, after the five most dramatic days in modern political history, Mr Cameron agreed a stunning deal that will mean Britain being governed by its first coalition administration since the 1930s.
The Tory leader paid an extraordinary price to bring Mr Clegg into the fold and now faces a battle to persuade his shell-shocked party that it is not too high.
Mr Cameron handed a clutch of seats around the Cabinet table to the Lib Dems and, despite the deep reservations of many of his MPs, agreed to a referendum on reform of Britain’s voting system.
The Lib Dems, who will sit around the Cabinet table, will be the first to do so since Sir Archibald Sinclair, Minister for Air in the wartime Cabinet, who gave the order to bomb Dresden.
Mr Clegg agreed that under the new Chancellor George Osborne, public spending cuts must begin at once to start to rebuild confidence in Britain’s ability to repay its massive debts.
He also accepted Tory ‘red lines’ on the EU, immigration and Trident.
But Mr Cameron is expected to have to shelve a flagship Tory pledge on inheritance tax and instead move towards the Lib Dem policy of raising the income tax threshold to £10,000.
Last night, he was summoned to Buckingham Palace with wife Samantha to be asked by the Queen to form the next government.
At 43, Mr Cameron becomes Britain’s youngest Prime Minister since Lord Liverpool in 1812.
After entering Downing Street just before 9pm last night, he took a telephone call of congratulations from U.S. President Barack Obama.
After five days of paralysis following the first hung Parliament for 36 years, crowds had begun to gather in Parliament Square yesterday to demand that the Lib Dems make up their minds over who they wanted to support.
Mr Clegg was accused of behaving like a ‘harlot’ after it emerged that he had been conducting secret talks with Labour while on the brink of a deal with the Conservatives.
Yesterday morning, Lib Dem negotiations with Labour were underway, and a small circle around Mr Brown believed a ‘rainbow’ coalition – roping in Scottish and Welsh nationalists, Northern Irish MPs and the single Green Party MP – could still be assembled to keep the Tories out of power.