Buckingham Palace declined to comment, in keeping with its long-standing policy of never responding to unofficial books. Clarence House has been contacted for comment.
The Duchess later said during the same visit to Castle Mey “they fundamentally don’t understand,” referring to the palace, according to the book.
A spokeswoman for the Duke and Duchess of Sussex has not yet responded to a request for comment.
Bower’s book claims to be a “characteristically explosive and thoroughly researched account of the rift between the Sussexes and the rest of the royal family, addressing every aspect of scandal and suspicion”.
The biography, titled Revenge: Meghan, Harry and the war between the Windsors, will be released July 21 and is serialized by The Times, The Sunday Times and The Sun.