King Charles made a surprise appearance at the first garden party of the season at Buckingham Palace, and disregarded what his royal aides had expected him to do.

Speaking on an episode of Palace Confidential, royal editor at the Daily Mail Rebecca English, who attended the event, said: “I was warned in advance that they might try to tweak it a little bit, that he might do 45 minutes to an hour of meeting the public and shake hands.

“But of course, he listened to none of that, and wanted to meet and greet as many people as possible.”

King Charles was able to attend the party after reportedly being given the “go-ahead” by his doctors, as the monarch is currently undergoing cancer treatment.

According to English, King Charles was in a “jolly mood” as he welcomed his thousands of guests.

Garden parties, a tradition at Buckingham Palace since the 1860s, serve as a way for the monarch to honour community members for their public service.

Attendees included Princess Anne, Prince Edward, Sophie, the Duchess of Edinburgh, and the Duke and Duchess of Gloucester.

Guests enjoyed mingling with members of the royal family and strolling around the grounds. They were also treated to tea and cake, with the royals’ website noting that around 27,000 cups of tea and 20,000 slices of cake are typically consumed at these events.

Male attendees traditionally wear morning dress or lounge suits, while women don day dresses paired with hats or fascinators. National dress and uniforms are also appropriate.