Theresa May becomes first female British PM since Margaret Thatcher

Britain gets new PM

LONDON -- Britain got a new prime minister on Wednesday. A career politician, Theresa May is the first woman to hold the office since Margaret Thatcher in 1990.

The change came quickly. "It's not been an easy journey, and of course we've not got every decision right," said former Prime Minister David Cameron, leaving office four years earlier than he'd planned.

David Cameron makes final remarks as UK Prime Minister

Cameron gambled and lost on the referendum for Britain to leave the EU.

He spoke during one last grilling in Parliament, that was less a grilling than a political stand-up routine, reports CBS News' Mark Phillips.

"Other than one meeting this afternoon with her majesty the queen, the diary for the rest of the day is remarkably light," he joked.

It's all a neat show of political theatrics. One prime minister leaves, another arrives. The characters change but the plot stays the same.

It's Theresa May's show now. The 59-year-old, long-serving cabinet minister was called to the palace by the queen and asked to form a new government.

What we know about Theresa May, the next British Prime Minister

May has run Britain's home office for six years, dealing with policing, immigration and other tough issues. She will now have to manage the toughest of them all -- the divorce from Europe that she had actually campaigned against.

"We are living through an important moment in our country's history," May said after she officially became prime minister. "Following the referendum we face a time of great national change."

But there's already controversy about one of Theresa May's first big appointments. She's made Boris Johnson, a divisive figure who was criticized during the Brexit campaign for using racist innuendo about President Obama, her new foreign minister.

He'll now have to sell Brexit to the world.