Theresa May took office as Britain’s prime minister on Wednesday afternoon, after her predecessor, David Cameron, tendered hisresignation to Queen Elizabeth II.
At Buckingham Palace, the queen asked Ms. May, who had been home secretary, to form a government. Ms. May, 59, is the queen’s 13th prime minister; the first was Winston Churchill. She is the second woman to hold the job, after Margaret Thatcher.
Arriving at 10 Downing Street with her husband, Philip, Ms. May gave her first remarks as prime minister, making an appeal for unity and calm.
“Not everybody knows this, but the full title of my party is the Conservative and Unionist Party, and that word unionist is very important to me,” she said. “It means we believe in the union — the precious, precious bond between England, Scotland, Wales and Northern Ireland — but it means something else that is just as important. It means that we believe in a union not just between the nations of the United Kingdom but between all of our citizens, every one of us, whoever we are and wherever we are from.”
Repeating almost word for word a speech she gave upon declaring her candidacy for the leadership of the Conservative Party, Ms. May vowed to fight the “burning injustice” of poverty; harsh treatment of blacks by the police; lack of university access for white working-class boys; mental illness; and pay disparities between women and men. She said that many Britons were struggling just to get by.
“The government I lead will be driven not by the interest of the privileged few, but by yours,” she said. “We will do we everything we can to give you more control over your lives.”
Ms. May had supported Britain’s remaining in the European Union, but tepidly, and she promised to respect the outcome of the June 23 referendum
Only an hour or so earlier, Mr. Cameron had stood at the same spot, with his wife, Samantha, and their three children.
“It has been the greatest honor of my life to serve our country as prime minister over these last six years, and to serve as the leader of my party for almost 11 years,” Mr. Cameron said. “My only wish is continued success for this great country that I love so very much.”
Mr. Cameron cited the nation’s economic recovery as his top legacy. “With the deficit cut by two-thirds, two and a half million more people in work, and one million more businesses, there can be no doubt that our economy is immeasurably stronger,” he said.
He also cited among his accomplishments the legalization of same-sex marriage, in 2013; changes to the education system; and reduced wait times for operations in Britain’s much loved National Health Service.
In his final parliamentary duty, Mr. Cameron took part for the last time inprime minister’s questions, the weekly ritual in which lawmakers interrogate the leader in often combative exchanges.
On Wednesday, the discussion was more respectful — and lighthearted — than usual, as Mr. Cameron’s political adversaries and allies paid tribute to him as he prepared to leave his office in 10 Downing Street for the last time as prime minister, a position he has held for six years.
“I’m told that there are lots of leadership roles out there at the moment: There’s the England football team, there’s ‘Top Gear,’ there’s even across the big pond the role that needs filling,” Danny Kinahan, a lawmaker from Northern Ireland, told Mr. Cameron jokingly, referring to the country’s soccer team, a popular television show and the United States presidential election.
Jeremy Corbyn, the embattled leader of the opposition Labour Party, congratulated Mr. Cameron for his support for same-sex marriage and for his efforts to secure the release of Shaker Aamer, a Saudi citizen and British resident, from Guantánamo Bay last fall. He pressed Mr. Cameron, however, on his record on homelessness; the affordability of housing; and the rise of “zero hour” contracts that can exploit low-wage workers.
Mr. Cameron said his government had reduced child poverty and cracked down on mistreatment of workers.
The two men, in their final joust at Westminster, tangled over the respective challenges their leadership has faced. Mr. Cameron announced his resignation in the aftermath of Britain’s tumultuous referendum on June 23 to leave the European Union, while Mr. Corbyn, only 10 months into his term as the head of Labour, faces a challenge to that leadership.
Mr. Cameron said his governing Conservative Party had swiftly picked his successor, while saying of the opposition party, “They haven’t even decided what the rules are yet.”
Mr. Cameron also made a reference to the cat at 10 Downing Street, a tabby named Larry, who belongs to the Civil Service. “The rumor that somehow I don’t love Larry — I do, and I have photographic evidence to prove it,” he said, holding up a photograph of the cat. “Sadly, I can’t take Larry with me.”
On a more somber note, Angus Robertson, a lawmaker from the pro-independence Scottish National Party, said that Mr. Cameron’s decision to call the referendum risked the breakup of the United Kingdom. Most voters in Scotland and Northern Ireland voted to remain in the European bloc, while most voters in England and Wales — with notable exceptions, including London — voted to leave.
Mr. Robertson said of Ms. May: “She plans to plow on with ‘Brexit’ regardless of the fact that Scotland voted to remain in the European Union. How does the outgoing prime minister think that all this will go down in Scotland?”
Ahead of his parliamentary appearance, Mr. Cameron told The Telegraph newspaper, “As I leave today, I hope that people will see a stronger country, a thriving economy and more chances to get on in life.”
Though Mr. Cameron won a general election only last year, he finds himself out of power at age 49. Mr. Cameron will be the youngest prime minister to relinquish the job since Archibald Primrose, the Earl of Rosebery, in 1895.
Before leaving Parliament on Wednesday, to laughter and applause, Mr. Cameron appeared to reflect on the transience of power, telling lawmakers: “I was the future once.”
Mr. Cameron will mainly be remembered as the prime minister who gambled — and lost — by holding a referendum in which he called on Britons to continue more than four decades of European integration.
When 52 percent of voters decided they wanted to leave the bloc in last month’s referendum, Mr. Cameron was left with little alternative but to resign.
Ms. May, who has served as home secretary for six years, is expected to promote several women to central positions in her cabinet, though it remains unclear whether those will include the jobs of chancellor of the Exchequer or foreign secretary.
Because she argued for Britain to remain inside the European Union, she is expected to give powerful positions to several of those who took the opposing view, to create a politically balanced cabinet.
One of her most delicate decisions will be what positions — if any — to offer figures such as Boris Johnson, the former London mayor, and Michael Gove, the justice secretary. Both men took leading roles in the campaign for withdrawal from the European Union, or “Brexit.”
While the power struggle in the Conservative Party is over for now, the one in the opposition Labour Party is just getting underway.
On Wednesday, Owen Smith, a Labour lawmaker who used to speak for the party on work and pensions issues, said he would run for the leadership.Angela Eagle, who used to speak for the party on business issues, announced on Monday that she would challenge Mr. Corbyn, who has refused to stand down despite the resignation of most of his leadership team in Parliament.
The Labour Party’s ruling body — the National Executive Committee —decided that Mr. Corbyn would automatically be on the ballot, without needing to collect the necessary nominations from lawmakers, a task he would have struggled to accomplish.
The committee also decided to suspend local party meetings for the duration of the leadership contest, in a move apparently prompted by allegations of intimidation of lawmakers and party members. The timetable for the leadership vote is expected to be announced on Thursday; the contest will probably conclude by the end of September.