Monarch will also meet leaders of countries where he is head of state before reception for overseas guests
King Charles is meeting Liz Truss at Buckingham Palace as the nation prepares for the funeral of Queen Elizabeth II on Monday, the climax of 11 days of national mourning.
Charles was scheduled to meet the prime minister in the 1844 room at Buckingham Palace at 12.15pm on Sunday, before meetings with prime ministers of countries where he is also head of state. They include Kausea Natano of Tuvalu; Gaston Browne of Antigua and Barbuda, and James Marape of Papua New Guinea.
The King met other Commonwealth leaders on Saturday including the Canadian, Australian and New Zealand prime ministers, Justin Trudeau, Anthony Albanese and Jacinda Ardern.
There has been speculation that some countries might choose to become republics after the Queen’s death, but Ardern said on Sunday that she had no intention of instigating that process for New Zealand, although “there will continue to be an evolution in our relationship”.
The King met Truss last Saturday after the accession ceremony at St James’s Palace. The pair will meet for weekly audiences when parliament is sitting.
Later on Sunday, the King and Camilla, the Queen Consort, joined by other members of the royal family, will host a reception for heads of state and official overseas guests at Buckingham Palace, including the US president, Joe Biden.
At 8pm, the country will be invited to observe a minute’s silence. An interview with the Queen Consort will be broadcast on the BBC in which she will speak of how Queen Elizabeth II was a “solitary woman” in a male-dominated world.
She will add: “I can’t remember anyone except the Queen being there.” Giant screens are being erected in various locations across the UK to broadcast the service, including Hyde Park in London and Coleraine Town Hall in Northern Ireland. About 125 cinemas will also screen the event.
Meanwhile, people have been urged not to travel to join the queue for the Queen’s lying in state, which is due to close on Sunday.
The Department for Digital, Culture, Media and Sport said: “Queue times are already 13.5 hours and may increase. To avoid disappointment, please do not set off to join the queue.”
Transport for London is preparing for about one million people to visit the capital on the day of the funeral and the police have described it as their “biggest ever event”, involving 10,000 officers on duty.
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About 250 extra rail services will run – including some overnight trains – and National Highways has suspended planned motorway closures across England.
The former archbishop of York John Sentamu said the funeral service, which will start at 11am on Monday at Westminster Abbey, would be uplifting.
“The Queen does not and did not want what you call long, boring services; you’re not going to find boredom, but you’re going to be lifted to glory as you hear the service,” he said.
“The hearts and people’s cockles will be warmed, and at the same time, there will be a moment of saying this is a funeral service that is glorious in its setting.”