Why Queen won't return to Buckingham Palace to appoint new British Prime Minister

The Queen is unable to travel to Buckingham Palace from the Balmoral estate in Scotland to receive the UK's new Prime Minister next week.

In a tradition that predates Her Majesty's reign, the sovereign always greets the outgoing and incoming prime minister of the United Kingdom at Buckingham Palace in London.

But, for the first time since 1908, Boris Johnson and his successor - either Liz Truss or Rishi Sunak - will have to travel 1600km up to Aberdeenshire to meet her.

The shock development comes amid growing health concerns for the 96-year-old monarch.

Queen Elizabeth II is unable to travel to Buckingham Palace from the Balmoral estate in Scotland to receive the UK's new Prime Minister next week. Photo / AP

It was reported last week that Prince Charles is making "regular, daily" visits to his mother, which is seen as unusual.

The heir to the throne does not usually make unplanned visits to the Queen - they are most often arranged by palace officials.

Prince Andrew has been staying with the Queen at Balmoral, which is where she spends most of her summers.

The monarch was last seen in public on July 21 as she arrived at Aberdeen Airport.

Traditionally, the outgoing Prime Minister visits the Queen at Buckingham Palace after resigning or losing an election.

The leaving PM advises the Queen on who commands a majority of MPs in the House of Commons and should lead the country next.

Minutes later, the incoming PM then meets the Queen and "kisses hands" with Her Majesty.

In the past, it was a requirement to actually kiss the sovereign's hands, however "kissing hands" now just refers to the meeting between the Queen and the new PM.

Truss, the UK's Foreign Secretary, is the frontrunner to become the new Prime Minister when the results of the Conservative Party's leadership contest is announced on Monday evening.

Her Majesty has made a sudden change and broken with a tradition that dates back decades. Photo / AP

The winner of the vote will become the 15th PM during the Queen's reign.

It will be the first time a monarch has received a new Prime Minister outside Buckingham Palace since 1908.

On that occasion, King Edward VII asked Herbert Asquith to travel to Biarritz, in southwest France, where he was on holiday.

Queen Victoria regularly requested that new Prime Ministers visit her in Balmoral.

The Queen's health has been of growing concern since her husband Prince Philip's death last April.

She was forced to pull out of the Remembrance Day service last November because of a sprained back.

Her Majesty was also forced to isolate after coming down with Covid, which she stoically shook off while holding meetings virtually.

She then pulled out of a series of events surrounding her Platinum Jubilee, including the Service of Thanksgiving at St Paul's Cathedral and the Epsom Derby.

The Queen has also been seen using a cane and buggy to help her deal with "episodic mobility" issues.