Sir Keir Starmer phoned the King this morning to inform him of his plans to resign as Labour leader and step down as the UK Prime Minister. Charles picked up the call from his private home, Highgrove House in Gloucestershire.

But with a new prime minister on the way, we look at how many leaders have served under King Charles in the nearly four years he's been on the throne.

When the King ascended the throne in September 2022, Liz Truss was the Conservative Prime Minister. However, after a reckless mini-budget unveiling £45bn of tax cuts, the markets plunged into chaos and reduced the value of the pound, and she was forced out by her own party.

After just 49 days in office, she quit, prompting another Tory leadership election just months after Boris Johnson stepped down as PM.

This result led to Rishi Sunak being selected and sworn in as the new Prime Minister.

However, when the nation went to the polls in July 2024, they chose to back Labour – marking the end of his time in No10 and marking the start of Sir Keir's tenureship.

Whoever replaces him as Prime Minister will therefore become the King's fourth in as many years.

Although Sir Keir has resigned, he will stay in post as Prime Minister until a successor has been chosen by the Labour Party. During this time, he will still hold his weekly audiences with the King.

Over Queen Elizabeth II’s impressive 70-year reign, she was served by 15 prime ministers.

Each one served an average of four years and seven months, with six serving over five years.

They navigated the country through the Cold War, economic crashes, huge societal change and the war on terror.

Meanwhile, in the past 10 years, the UK has seen six prime ministers – and is about to welcome its seventh.