Writing in the Express, Hugo Vickers said the request may have been declined due to concerns the castle was not appropriate.

He wrote: “There are empty bedrooms and suites in the private apartments within Windsor Castle which the Sussexes may have had their eye on, or perhaps some former living quarters in the castle grounds converted into other things.

“But I can see how it might not be entirely appropriate to have a young family living there.”

The couple, who have two children, live in the Melicito area of California after quitting the Royal Family in 2020.

Windsor Castle, which has been the site of a royal residence for centuries, was the favoured home of the late Queen during her later years.

Generations of royals are buried at the site, including the former monarch and her husband Prince Philip.