Prince Harry said he has even more gossip about King Charles and Prince William, with enough material to write a second book.
Just days after his memoir Spare was published, the Duke of Sussex said he avoided mentioning some anecdotes about his father and brother, as he feared they would never forgive him if he revealed them.
Harry said the original transcript for his book was twice the length of the final draft and many details about interactions between him, Charles and William were edited out as there were things he didn't want the world to know.
He explained the first draft of Spare was 800 pages, but the book was now 400 pages long.
Harry told The Telegraph: "It could have been two books, put it that way. And the hard bit was taking things out."
The Duke added: "There are some things that have happened, especially between me and my brother, and to some extent between me and my father, that I just don't want the world to know. Because I don't think they would ever forgive me."
Harry admitted he had 50 Zoom calls with his ghostwriter and at times struggled to decide which details to include and which ones to leave out of his memoir.
Spare, which was published globally on Tuesday, was boosted into the record books with 400,000 hardback, e-book, and audio format copies being snapped up, its publisher said.
Larry Finlay, managing director of Transworld Penguin Random House, said: "We always knew this book would fly but it is exceeding even our most bullish expectations.
"As far as we know, the only books to have sold more in their first day are those starring the other Harry (Potter)."
Bookshops in the UK opened early on Tuesday to offer Harry's book - but queues were sparse after leaks ahead of the publication, with industry experts predicting Spare would be one of the best-selling pre-order titles of the past decade.
It is being sold for £14, not the recommended retail price of £28, in places such as Waterstones and WHSmith as well as online at Amazon.
Explosive details from the memoir, including that Harry's brother Prince William allegedly assaulted him in a row over Meghan Markle, have caused shockwaves. The Royal Family has not commented or responded to the claims.
