LONDON (AFP) – Conservative leader David Cameron on Wednesday got down to business as British prime minister heading a historic centre-right coalition that finally ended 13 years of Labour rule.
The 43-year-old Conservative Party leader -- Britain's youngest prime minister for two centuries -- took office after striking a deal with the third-placed Liberal Democrats, whose leader Nick Clegg becomes deputy premier.
Cameron's appointment by Queen Elizabeth II late Tuesday came after Labour leader Gordon Brown admitted defeat five days of political limbo following last week's inconclusive election.
Cameron acknowleged the huge challenges facing him, not least Britain's fragile recovery from the global economic crisis.
"This is going to be hard and difficult work. A coalition will throw up all sorts of challenges," he said in a speech in Downing Street, flanked by his pregnant wife Samantha.
"But I believe together we can provide that strong and stable government that our country needs based on those values -- rebuilding family, rebuilding community, above all rebuilding responsibility in our country," he added.
President Barack Obama called Cameron within minutes of his appointment, inviting him to visit the United States in July.
Other world leaders, including German Chancellor Angela Merkel, French President Nicolas Sarkozy and Australian Prime Minister Kevin Rudd also quickly called Cameron to congratulate him.
Clegg was joined by four other Lib Dem ministers in Cameron's coalition government, after backing the deal to form Britain's first coalition government since World War II.
"We are going to form a new kind of government," Clegg told his lawmakers, adding he hoped it marked "the start of the new politics I have always believed in."
Key Conservative appointments included 38-year-old George Osborne as finance minister -- facing daunting economic challenges including a eurozone crisis -- and William Hague as foreign minister.
The dramatic confirmation of Britain's new leader came after days of uncertainty following Thursday's election, which produced no clear winner for the first time since 1974.
Brown announced he was quitting just an hour and a half before Cameron walked through the front door of 10 Downing Street.
He wished Cameron well as he departed top-level politics, while acknowledging the personal weaknesses -- such as poor presentational skills and impatience -- which hampered his three-year premiership.
"Only those who have held the office of prime minister can understand the full weight of its responsibilities and its great capacity for good," Brown said.
His Labour party's deputy leader Harriet Harman will act as caretaker leader while a leadership campaign takes place, which is expected to conclude by September.
In the election, the Conservatives won 306 seats in the 650-member House of Commons -- 20 short of a clear majority of 326 -- followed by Labour on 258 and the Lib Dems on 57.
After five days of talks between the Lib Dems and Tories -- and briefly between the Lib Dems and Labour -- the two parties finally struck a deal.
Clegg is leading a Liberal party into British government for the first time since David Lloyd George left power in 1922.
Critics say the deal between the centre-right Conservatives and centrist Lib Dems is an unlikely alliance, since they have strongly differing views on a number of issues.
But between them, they have enough to secure a majority in the House of Commons which Labour and the Lib Dems, seen as more natural bedfellows, did not.
There were already doubts about the political union Wednesday, however, with the Conservative-supporting Telegraph newspaper warning it would be "unsatisfactory and short-lived."
"Even as they applauded the statesmanship of their leaders, there were voices in both parties predicting the marriage would not last," added the Financial Times.