London, UK - Prince Harry has said he had enough material for two books, but he held back because he does not think his father and brother would "ever forgive" him.

Harry's controversial memoir became the fastest selling non-fiction book ever when his tell-all tale lambasting the royal family was finally published this week.

The headline-grabbing autobiography Spare, which hit the shelves on Tuesday, dropped plenty of bombshells, including claims that William physically attacked him, and that King Charles III put his own interests above Harry's and was jealous of Meghan and Kate. It sold a record-breaking 1.4 million copies on just its first day of publication.

In a new interview with Bryony Gordon of The Daily Telegraph, Harry said: "It could have been two books, put it that way."

Gordon wrote that Harry told her the first draft was 800 pages - double the final manuscript, which comes in at just over 400 pages.

Harry told Gordon that there were things he revealed to ghostwriter JR Moehringer "for context," but there was "absolutely no way" they would be included in the book.

Harry said it is impossible to tell his story without referring to family members.

He added: "But 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.

"Now you could argue that some of the stuff I've put in there, well, they will never forgive me anyway.

"But the way I see it is, I'm willing to forgive you for everything you've done, and I wish you'd actually sat down with me, properly, and instead of saying I'm delusional and paranoid, actually sit down and have a proper conversation about this, because what I'd really like is some accountability.

"And an apology to my wife."

During the interview, Harry told Gordon that he knows the press "have got a sh*t-ton of dirt about my family. I know they have, and they sweep it under the carpet for juicy stories about someone else".

Harry also revealed that he worries about his brother William's children.

"And though William and I have talked about it once or twice, and he has made it very clear to me that his kids are not my responsibility, I still feel a responsibility knowing that out of those three children, at least one will end up like me, the spare. And that hurts, that worries me," he said.

Talking about his reasons for doing what he is doing, Harry said: "This is not about trying to collapse the monarchy, this is about trying to save them from themselves. And I know that I will get crucified by numerous people for saying that."

The interview in the Telegraph is the latest in a string which Harry has taken part in around the publication of his book.

The memoir sees Harry expressing his frustration at being the "spare to the heir," his anger at the British media, his unresolved trauma over the death of his mother, his mental health struggles, his lonely life before meeting Meghan, and the breakdown of his family relationships.