Queen Elizabeth welcomes Boris Johnson during an audience in Buckingham Palace, where she will officially recognize him as the new prime minister, in London, July 24, 2019.

Victoria Jones/Pool via REUTERS

Boris Johnson enters Downing Street in London. Johnson promised in his first speech as prime minister to lead Britain out of the European Union on Oct. 31 with "no ifs or buts" and warned that if the bloc refused to negotiate then there would be a no-deal Brexit.

REUTERS/Peter Nicholls

Boris Johnson is welcomed in 10 Downing Street by staff after meeting Queen Elizabeth. He took over from Theresa May at one of the most perilous junctures in post-World War Two British history - the United Kingdom is divided over Brexit and weakened by the three-year political crisis that has gripped it since a 2016 referendum vote to leave the bloc.

Stefan Rousseau/Pool via REUTERS

Boris Johnson is welcomed in 10 Downing Street by staff. Just hours after arriving in Downing Street, the new Conservative Prime Minister began work with one of the biggest culls of senior government jobs in recent British history, changing all of the main ministers. Most of his appointees were Brexit supporters.

Stefan Rousseau/Pool via REUTERS

Boris Johnson enters Downing Street. REUTERS/Hannah McKay

Boris Johnson's girlfriend, Carrie Symonds, is seen outside Downing Street. When Johnson entered the famous black door of No. 10 Downing Street, he was the first for nearly half a century to do so unaccompanied by a spouse. Instead of walking through the door with him, his girlfriend Symonds, former head of communications for his Conservative Party, stood nearby with his staff - a sign of a colorful private life that arguably represents modern Britain better than the traditional picture. But Symonds' presence before the cameras, on the sidelines if not by his side, suggests things may slowly be changing.

REUTERS/Toby Melville

Boris Johnson's girlfriend, Carrie Symonds, is seen outside Downing Street. If Symonds joins Johnson in his official residence, at 31 she will be the youngest partner of a prime minister in 173 years. By moving in together unmarried, they would be doing something that the vast majority of committed couples do in Britain these days - even if they would be the first to do so openly at No.10.

REUTERS/Peter Nicholls

Theresa May looks on outside Downing Street, on her last day in office as Britain's prime minister. REUTERS/Hannah Mckay

Theresa May arrives to deliver a speech on her last day in office as Britain's prime minister. REUTERS/Peter Nicholls

Boris Johnson delivers a speech outside Downing Street. REUTERS/Peter Nicholls

Boris Johnson is driven into Buckingham Palace in London. There was a moment of drama in Johnson's passage to power as he drove to Buckingham Palace for his audience with Queen Elizabeth and his formal appointment. Greenpeace protesters tried - but failed - to block the path of his car as his chauffeur drove around them.

REUTERS/Henry Nicholls

Boris Johnson arrives at Buckingham Palace for an audience with Queen Elizabeth. Yui Mok/Pool via REUTERS

People hold placards as they demonstrate against newly appointed British Prime Minister Boris Johnson outside Downing Street. REUTERS/Hannah McKay

Theresa May and her husband Philip wave outside Downing Street, on her last day in office. REUTERS/Hannah Mckay

A protester wearing a mask depicting Boris Johnson is seen in front of Buckingham Palace. REUTERS/Henry Nicholls