Prince Harry says he has enough material to write another memoir and chose not to publish some details as he was concerned his father and brother would never forgive him if they were made public.
In an interview with the Daily Telegraph, the Duke of Sussex also said the initial transcript for Spare was twice the length of the final draft and he had found it difficult to work out what to remove.
A lot of the detail that was eventually edited out, he added, concerned both his father and his brother.
“The first draft was different,” he told interviewer Bryony Gordon. “It was 800 pages, and now it’s down to 400 pages. It could have been two books, put it that way. And the hard bit was taking things out.”
He 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.”
Spare went on sale on Tuesday in the UK but it had already been heavily trailed after copies accidentally went on sale in Spain early.
The Guardian was the first to reveal details from the memoir including the allegation that Prince William had attacked Harry following a tense discussion over Meghan, the Duchess of Sussex.
Kensington Palace and Buckingham Palace have said they will not comment on the contents of the book.
Prince Harry also speaks about what he claims was a lack of support for him and Meghan.
News of surplus material is likely to cause further consternation for the royal family.
In the interview, Harry said he knew he would “get trashed” for including anything about his family but that he could not have written the memoir without including them.
He was also critical of the press and alleged that the media had “a s--t tonne of dirt about my family, I know they have, and they sweep it under the carpet for juicy stories about someone else”.
The duke reiterated that he was not trying to destroy the monarchy, but instead help reform it.
Referring to Prince William’s children – George, nine, Charlotte, seven and Louis, four – Prince Harry said at least one of his brother’s children will be a “spare” and that this “hurts” and “worries” him.
“This is not about trying to collapse the monarchy – this is about trying to save them from themselves,” he added. “I know that I will get crucified by numerous people saying that.”
He suggested that in time the royal family could thank him for talking so openly about his trauma.
Meanwhile, he admitted that trying to change “an institution” and the media landscape was “no small task” but that he was adopting “long-term, strategic thinking” to see through this “enormous” challenge.
