Starmer received the blessing of King Charles III to form a government.

A photo of the occasion served as the official announcement of Starmer’s new title.

Starmer is now headed from Buckingham Palace to take up residence in No. 10 Downing Street, where he is expected to speak.

Labour leader Keir Starmer had, earlier, arrived at Buckingham Palace to accept the request of King Charles III to form a government after his party’s landslide victory.

In a ceremony known as the “kissing of hands,” Starmer has officially become UK prime minister. 

Starmer’s arrival at the palace is part of the choreography of changing governments that harkens back to a time when the king exercised supreme power and chose his preeminent minister – the prime minister – to run his government.

The modern-day constitutional monarchy echoes that tradition, with the king officially offering the post to the party that holds a majority in the House of Commons.

Earlier in the day, outgoing Prime Minister Rishi Sunak departed from Buckingham Palace following his resignation as prime minister late Friday morning after the Conservative Party suffered staggering losses in the general election.

Britain's outgoing Prime Minister and leader of the Conservative party, Risihi Sunak, watched by his wife Akshata Murty, delivers a statement after his general election defeat, outside 10 Downing Street in London. AFP

He left 10 Downing Street after giving his final speech as prime minister, hours suffering a landslide defeat by the left-of-centre Labour Party, which will form a government for the first time in 14 years.

Sunak said earlier that he took responsibility for his party’s loss, and that he had called Labour leader Keir Starmer to congratulate him on his victory.

Voters in the UK cast their ballots Thursday in a national election to choose the 650 lawmakers who will sit in Parliament for the next five years. With almost all results counted, Labour, led by Starmer, has gained at least 400 seats in Parliament.

A ballot box is emptied at the Richmond and Northallerton count centre in Northallerton, north of England. AFP 

After more than a decade in power under five different prime ministers, Sunak ’s Conservatives are set to have their seats in the 650-seat House of Commons cut down to around 130. That would be the Tories’ worst result in the party’s two-century history and one that would leave the party in disarray.