Theresa May became British prime minister on Wednesday after being appointed by British Queen Elizabeth II shortly after the monarch accepted David Cameron's resignation.
An official image showed May curtseying to the queen during an audience at Buckingham Palace. Under Britain's unwritten constitution, it is up to the monarch to ask the leader of the party that commands a majority in the House of Commons to form a government.
The 59-year-old Conservative party leader is the second woman PM of Britain after Margaret Thatcher. The tough-talking leader took charge with a heavy workload already waiting in her in-tray after the Brexit vote.
David Cameron visited British Queen Elizabeth II earlier to tender his formal resignation, after stepping down in the wake of the seismic vote to leave the European Union.
In a final statement in front of Downing Street, flanked by his wife and three children, he said it had been "the greatest honour of my life" to work there, adding: "My only wish is continued success for this great country that I love so very much."