Prince Harry’s upcoming tell-all is said to be worrying the British royal family months before it hits bookshelves.

In October, Penguin Random House announced that the Duke of Sussex’s memoir, titled "Spare," is coming out on Jan. 10. According to the publisher, the story is told with "raw, unflinching honesty" and filled with "insight, revelation, self-examination and hard-won wisdom about the eternal power of love over grief." Within hours of the announcement, "Spare" skyrocketed to the top 10 bestseller list on Amazon.

"Oh my gosh, I think they’re shaking in their boots over this," author Christopher Andersen told Fox News Digital. "I think that they’ve done everything they [could] to persuade Harry not to publish this book… I just think if you look at what happened in [Queen Elizabeth II’s] funeral, I don’t see fences being mended. I thought that Harry looked very unhappy. Of course, his grandmother just died. But beyond that, there were no affectionate moments. No one was singing ‘Kumbaya’ by any means."

Prince Harry's book cover for Spare

Prince Harry's memoir, titled ‘Spare,’ is coming out on Jan. 10 whether the British royal family likes it or not. (Penguin Random House)

Andersen has recently written a book about the 38-year-old’s father titled "The King: The Life of Charles III." He spoke to numerous palace insiders, as well as those who have known the queen’s eldest son or worked with the 74-year-old closely over the years.

PRINCE HARRY DIDN’T MAKE ANY CHANGES TO HIS MEMOIR ‘SPARE’ AFTER QUEEN ELIZABETH’S DEATH, AUTHOR CLAIMS

According to Andersen, the king "still has affection" for his youngest son and is hopeful he can bring the family back together again.

"I’m sure he wants to mend the rift between Harry and [his older brother Prince] William," Andersen explained. "How [is he] going to be able to do that with this book looming on the horizon with more revelations? … It’s gotta be adversely impossible, I think."

Prince William and Prince Harry standing vigil

Queen Elizabeth's grandchildren (L-R) Britain's Prince Harry, Duke of Sussex and Britain's Prince William, Prince of Wales, standing vigil around her coffin on Sept. 17, 2022. Britain's longest-reigning monarch passed away on Sept. 8 at age 96. (Getty Images)

"I think that Charles is between a rock and a hard place here," he shared. "If Harry and Meghan [Markle] aren’t going to be working royals, then he wants to follow his mother’s dictum. And that is, if you’re not full-time, you’re out. But by the same token, he needs all hands on deck… It’s going to be interesting to see what happens in the future."

Andersen said he was stunned to hear that initially, Harry was not allowed to wear his military uniform for the queen’s vigil. After sparking backlash, the palace announced he would be allowed to wear his uniform to stand vigil around the queen’s coffin. He wore a suit for the funeral.

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Prince Edward, Prince Andrew and King Charles standing vigil

King Charles lll, right, Prince Andrew, Duke of York, center, and Prince Edward, Earl of Wessex, left, attend a vigil, following the death of Queen Elizabeth ll, inside Westminster Hall on Sept. 16, 2022 in London. (Photo by Daniel Leal - WPA Pool / Getty Images)

"[Prince] Edward was permitted to wear a uniform and he’s never served in the military," said Andersen. 

"[Prince] Andrew, with all of his problems, was permitted to wear a uniform… but Harry wasn’t… That initial laying down of the law by Charles or refusal to bend in the beginning, I thought, was alarming. And actually, if anybody deserves to wear a uniform in the royal family, it’s Harry. I mean, 10 years in the army and actually serving in combat in Afghanistan. He certainly earned that, right? And I think he was hurt by that. I think he was hurt by the kind of lack of attention that [he and his wife] were getting in London from the rest of the family and they couldn’t wait to get back in the U.S."

Meghan Markle smiles

In his book "The King," author Christopher Andersen alleged that at first, King Charles did not know Meghan Markle was biracial. (Getty Images)

According to Andersen’s book, Charles found Markle, a former American actress, to be "completely charming, absolutely delightful." Andersen alleged that initially, Charles had no idea the former "Suits" star was biracial because she "bore a passing resemblance" to Kate Middleton’s sister, Pippa. "Not that it would have mattered at all, of course," he allegedly told an American pal. "But no, I didn’t realize that until much later."

Harry married Markle, 41, in 2018. But in 2020, the Duke and Duchess of Sussex announced they were stepping back as senior members of the British royal family. They moved to California and soon gave a bombshell interview in 2021 with Oprah Winfrey.

King Charles saluting

Prince Harry told Oprah Winfrey in March 2021 that his father King Charles III, pictured, had cut him off financially. (Getty Images)

The couple spoke of Markle's deep unhappiness with her new life in England, the alleged racism within the royal family and Harry’s fear that his wife’s life might be endangered had they remained in his native country. Harry also told Winfrey that his family cut him off financially and that he helped pay for his security with money left to him by his mother. They have launched numerous initiatives, including a Netflix production deal and the nonprofit Archewell Foundation.

PRINCE HARRY’S MEMOIR 'SPARE' CAN 'BE A DANGER’ TO THE ROYAL FAMILY, EXPERT SAYS

Prince Harry at Queen Elizabeth's funeral

Prince Harry reunited with his family in September to mourn the passing of his grandmother, Queen Elizabeth II. He resides in California with his wife Meghan Markle and their two children, Archie and Lilibet. (Getty Images)

Penguin Random House’s announcement about "Spare" included a statement from Harry.

"I’m writing this not as the prince I was born but as the man I have become," he said. "I’ve worn many hats over the years, both literally and figuratively, and my hope is that in telling my story — the highs and lows, the mistakes, the lessons learned — I can help show that no matter where we come from, we have more in common than we think."

The book had been tentatively scheduled for publication this year, and the delay led to rumors that Harry was hesitating to say too much about his family, or was perhaps revising the narrative after his grandmother died in September. He has spoken of being estranged from his brother, although the siblings and their wives appeared in public together during the mourning period following the queen’s death.

The once Fab Four looking somber at Queen Elizabeth II's funeral

From left: Prince Harry, Duke of Sussex, Meghan, Duchess of Sussex, Prince William, Prince of Wales and Catherine, Princess of Wales leaving after a service for Queen Elizabeth II on Sept. 14, 2022. Christopher Andersen alleged that the relationship between Harry and William is still strained. (Photo by Emilio Morenatti / POOL / AFP via Getty Images)

Financial terms for the book were not disclosed. However, Harry will donate proceeds from "Spare" to British charities. He has already given $1.5 million to Sentebale, an organization he co-founded with Prince Seeiso of Lesotho to help children and young people in Lesotho and Botswana affected by HIV/AIDS.

The Associated Press contributed to this report.