She flew back by helicopter to the 950-year-old royal fortress from the Sandringham estate in Norfolk where she had spent a long weekend. The 95-year-old monarch is under doctors' orders to rest after spending a night in hospital three weeks ago for a mysterious ailment. Aides hope to give an update later this week on her fitness for duties. She had "preliminary investigations" at the private King Edward VII's Hospital in London on October 20 after suddenly cancelling an important visit to Northern Ireland.

       Restricted on medical advice to light duties such as going through state papers in her official red boxes and holding virtual audiences by video link, she also pulled out of attending the COP26 UN climate change conference in Glasgow last week. She chose instead to record a video message.

       This weekend she will stay away from the annual Festival of Remembrance at the Royal Albert Hall on Saturday night.

       The Queen plans to attend the annual Remembrance Sunday wreath-laying service at the Cenotaph in Whitehall this Sunday to honour Britain's war dead, which is one of the most sacred events in her annual calendar.

       It would be her first in-person event since a reception on October 19. The fact she was considered well enough to travel to Sandringham was regarded by royal watchers as a positive sign.