British Labour Party leader Gordon Brown has promised "a new government with new priorities," after taking on the mantle from Tony Blair as British Prime Minister.
Mr Brown, the former Chancellor of the Exchequer, smiled broadly following a meeting at Buckingham Palace during which Queen Elizabeth asked him to form a new government in the traditional transfer of power.
An emotional Tony Blair had just resigned as prime minister after a decade in power, clearing the way for Mr Brown to take command of the government.
Tony Blair
Mr Blair submitted his resignation to the queen during a 25-minute closed-door meeting at Buckingham Palace. With his wife, Cherie, he waved to reporters and then traveled to his constituency in northern England, where he is expected to resign as an MP to take up his post with the Quartet of Mideast peace mediators.
Mr Brown, a 56-year-old Scot known for his often stern demeanor, beamed as he was applauded by Treasury staff before heading with his wife, Sarah, to the palace to be confirmed as prime minister.
Mr Blair received a warm send-off in the House of Commons, from his opponents as well as members of his own Labour party, after one final appearance at the weekly question time session.
"I wish everyone - friend or foe - well. And that is that. The end," he said.
Legislators rose to their feet and applauded as he left for his meeting with the queen. Some, including Foreign Secretary Margaret Beckett, wiped away tears.
Mr Blair also used the session to say he was sorry for the perils faced by British troops in Iraq and Afghanistan, but he gave no apology for his decisions to back the United States in taking military action.
He expressed his condolences to the families of the fallen, this week including two in Iraq and one in Afghanistan.
"I am truly sorry about the dangers that they face today in Iraq and Afghanistan," Blair said.
"I know some may think that they face these dangers in vain; I don't and I never will. I believe they are fighting for the security of this country and the wider world against people who would destroy our way of life," he said.
"Whatever view people take of my decisions, I think there is only way view to take of them: they are the bravest and the best," Blair added.
Tory leader David Cameron saluted Mr Blair's achievements and wished him well. "He has considerable achievements to his credit, whether it is peace in Northern Ireland, whether it is work in the developing world, which I know will endure," Mr Cameron said.
"I'm sure that life in the public eye has sometimes been tough on this family. So can I say on behalf of my party that we wish him and his family well, and we wish him every success in whatever he does in the future."
Workers packed furniture and boxes into a van outside Mr Blair's Downing Street home as he prepared to hand power to Mr Brown.
The incoming leader, who for many lacks the charisma of his predecessor, must woo Britons by shaking off the taint of backing the hugely unpopular Iraq war. With promises of restoring trust in government, he is planning to sweep aside the Blair era after a decade waiting for the country's top job.
Mr Brown will seek to head off a challenge from a revived opposition Conservative party. Polls already point to a "Brown bounce," with one survey putting his Labour party ahead of its rivals for the first time since October.
Less than two hours after Blair left the prime minister's 10 Downing Street residence for Buckingham Palace, Brown stood posing for photographs at the same black front door, every move captured by a throng of cameramen and photographers.
Onlookers and anti-Iraq war protesters gathered outside Downing Street while a crowd formed outside the palace.
Blair, whose rule began with high promises but ended with his popularity badly dented by the 2003 Iraq war, stepped aside to give the Labour Party a better chance of winning a fourth consecutive term in the next election, due in 2010.
Few expected the dour former finance chief to be greeted with public enthusiasm. In fact, Mr Brown's ascension was widely seen as a political gift for the more youthful Conservative chief David Cameron.
But Mr Blair's last full day in office brought an unexpected present - the defection of a Conservative legislator to his Labour party. The move put Mr Brown in bullish mood and he will now consider calling a national election as early as next summer.
US President George W Bush paid a final tribute to his ally and will later call Mr Blair's successor with congratulations.
"Tony's had a great run and history will judge him kindly," Mr Bush told The Sunnewspaper in remarks published this morning. "I've heard he's been called Bush's poodle. He's bigger than that."
In Europe, bridges have been built with German chancellor Angela Merkel and new French president Nicholas Sarkozy, but tensions are likely to emerge.
The succession of Mr Brown ends a partnership at the pinnacle of British politics that began when he and Mr Blair were elected to Parliament in 1983 - sharing an office and a vision to transform their party's fortunes.
It has been widely reported - but never confirmed - that the two men agreed a pact over dinner in 1994: Mr Brown agreeing not to run against Mr Blair for the Labour leadership following the death of then party chief John Smith.
In return, Mr Blair reportedly vowed to give Mr Brown broad powers as Treasury chief and to step down after a reasonable time to give Mr Brown a shot at the senior post.