Prince Harry and Meghan Markle are reportedly “sitting on a goldmine” when it comes to their next potential attack on the British Crown. About the Duchess of Sussex, royal author Tom Bower told an outlet, “The only thing she has got left — and I think that is her potential gold mine — is her autobiography.” “Eventually, Meghan is going to want to write her memoir, Harry is going to want to update Spare, and they are going to want to sit down and promote themselves on TV,” a Sussex insider shared. “They will not shy away from answering questions about the royals… For now, they’re biding their…