The revolving door of No 10 has yielded three prime ministers in the less than two years has been on the throne.

So as “kissed hands” – a historical term for what is essentially these days a mere handshake – with the sovereign at Buckingham Palace, the king perhaps, like much of the rest of the country he heads, may have hoped it was a ceremony he would not be performing again in the near future.

Starmer is Charles’s first prime minister, and the first leader he has appointed after a general election.

But as we are constantly told, the sovereign rises above political partisanship, so that should make no difference. Personal chemistry, however, is not proscribed by protocol. The late Queen Elizabeth II’s favourite of her 15 prime ministers was said to be Labour’s Harold Wilson because of his easy manner.

Early indications are that these two men enjoy a warm rapport. They are certainly not strangers, and will see each other frequently, not least for the prime minister’s weekly audience.

It was the king, as Prince of Wales, who personally knighted the former director of public prosecutions when he became a Knight Commander of the Order of the Bath at an investiture ceremony in the palace ballroom in 2014 for services to law and criminal justice.

At the recent state visit for the emperor and empress of Japan, Starmer was seated next to Charles’s right-hand man, Clive Alderton. Rishi Sunak was placed next to a computer scientist from Southampton.

As Labour leader, Starmer also attended the king’s white-tie banquets at the palace, for the South Korean and South African state visits.

The two were seen engrossed in conversation at a reception in St James’s Palace before the Ukraine recovery conference in 2023, and photographed exchanging friendly greetings after the late queen’s death.

The king might have been alarmed when in 2021 footage surfaced showing the then human rights barrister telling a film-maker in 2005: “I also got made a queen’s counsel which is odd, since I often used to propose the abolition of the monarchy.”

Charles may, however, have been reassured by Starmer’s dismissal of these republican tendencies as youthful indiscretion, and the new prime minister has since made clear he does not want abolition, but would like to “downsize it”.

Starmer has demonstrated his strong support of the king and was even invited to Charles’s first “dine and sleep” – a dinner party and overnight stay at Windsor Castle – in March 2023. , as leader of the opposition, at Elizabeth II’s funeral, the king’s accession council and his coronation, and has been a member of the privy council since 2017.

The two may have much in common on issues such as the Rwanda scheme, which Charles , as well as on the climate crisis and homelessness, on which the king as Prince of Wales has been vocal in the past.

As the historian Ed Owens told : “A Labour government under Keir Starmer will be more attuned to the plight of people as a social issue.

“These kinds of issues have long been on the radar of the king. There’s a meeting of minds in terms of the social issues at stake.”