The palace was on "tenterhooks" as they waited for the day to come, expert Angela Levin claimed.
"They have lawyers ready to read it but they won't see it until it's out," she said. "If it's too bland it won't be worth the millions they've already paid him."
As OK! previously reported, the red-headed royal, 38, announced his latest endeavor last year, but there were hardly any details given.
Now, Penguin House is sharing more and more about the new tome.
"It was one of the most searing images of the twentieth century: two young boys, two princes, walking behind their mother’s coffin as the world watched in sorrow — and horror. As Diana, Princess of Wales, was laid to rest, billions wondered what the princes must be thinking and feeling — and how their lives would play out from that point on. For Harry, this is that story at last. With its raw, unflinching honesty, Spare is a landmark publication full of insight, revelation, self-examination, and hard-won wisdom about the eternal power of love over grief," the description reads.
“Penguin Random House is honored to be publishing Prince Harry’s candid and emotionally powerful story for readers everywhere,” Penguin Random House CEO Markus Dohle said in a press release. “He shares a remarkably moving personal journey from trauma to healing, one that speaks to the power of love and will inspire and encourage millions of people around the world.”
"The book has been back and forth between Harry and JR Moehringer and the publishers a few times," the source spilled, referring to Harry's ghost-writer. "They wanted more than was in the first draft, and then Harry wanted to refine things after the Queen passed away."
"But there has been extra toing and froing that people don’t know about," the source continued. "This is because the publishers wanted more areas covered and more detail on some things that were already included."
For more on the royal family, tune into the new podcast "The Firm: Blood, Lies and Royal Succession." Listen below!