But the general public will be able to visit the Queen's resting place when the castle reopens on September 29.

Some areas within royal residences reopened to tourists on Thursday, including the Queen's Gallery at Buckingham Palace, the Palace of Holyroodhouse and the Queen's Gallery in Edinburgh, Scotland, according to the Royal Collection Trust.

Additionally, special displays marking the Queen's Platinum Jubilee at Buckingham Palace, Windsor Castle and the Palace of Holyroodhouse will not reopen to the public, the trust added.

The photograph of the ledger stone comes a day after Buckingham Palace released a new portrait of King Charles III with the sovereign's signature red boxes.

"The image was taken in the Eighteenth Century Room at Buckingham Palace last week and shows His Majesty The King carrying out official government duties from The King's Red Box," the palace said in a statement.

The red boxes contain important papers from government ministers in the UK and from representatives across the Commonwealth and beyond.

"The documents are sent from the Private Secretary's Office to The King, wherever he may be in residence, in a locked red despatch box," it added.

In the background behind the new monarch is a black and white photograph of the late monarch and Duke of Edinburgh, which was a Christmas gift to the couple from King George VI in 1951.