David Cameron became prime minister of the U.K. this evening (London time). In contrast to a head-of-government transition in the U.S., which involves a huge outdoor ceremony, the British hand-over of power occurs in a private meeting with Queen Elizabeth II at Buckingham Palace, in which she invites him to form her government.
British media are making much of the fact that, at the age of 43, Cameron is the youngest prime minister in 198 years. However, he is less than one year younger than Tony Blair was, when he had a similar meeting with The Queen, in 1997.
An odd story is emerging. After Cameron's predecessor, Gordon Brown, had delayed his resignation for five days after the general election, once he decided to leave, he reportedly was in such a hurry, that he didn't confirm with the Conservatives and Liberal Democrats that their coalition was in place, before he resigned. According to a blog on the website of The Times, Liberal Democrats were "hacked off" at Brown, for upsetting the timing of the coalition negotiations.
There's still no official word on the shape of the coalition. There are several media reports that Nick Clegg, leader of the Liberal Democrats, will be deputy prime minister. While that has been a somewhat meaningless title in single-party governments, I suspect it might carry more weight in a coalition government. For example, in Britain's World War II coalition government under Winston Churchill, Labour leader Clement Attlee, as deputy prime minister, was more of less in charge of domestic policy, while the prime minister was preoccupied with the war.
The circumstances are different, now. But Cameron may need to allow Clegg to play a major role, in order to keep Clegg's party committed to the coalition.