Princess Diana’s biographer Andrew Morton believes the British royal family will put on a united front while the Duke and Duchess of Sussex tell all – again.

After the couple was honored at the glitzy Ripple of Hope gala on Tuesday, Netflix will drop the first installment of their docuseries titled "Harry & Meghan" on Thursday. It promises to detail their struggles in the public eye. The second installment will be available on Dec. 15. Then on Jan. 10, Harry’s highly anticipated memoir "Spare" will hit bookshelves.

The couple has already addressed their problems with the royal family in a bombshell interview with Oprah Winfrey that aired in 2021.

Prince Harry's book cover for Spare

Prince Harry's memoir, titled ‘Spare,' will hit bookshelves on Jan. 10. (Penguin Random House)

"Harry’s got every right to write his memoir," Morton told Fox News Digital. "He’s not the first royal to do so, nor will he be the last. It goes back to Edward VIII. He wrote ‘A King’s Story’ in 1951, which was an international bestseller like this one’s going to be. And it upset the royal family. Diana wrote with me, ‘Her True Story’ – international bestseller, upset the royal family. [The former] Prince Charles, the Prince of Wales wrote his book with Jonathan Dimbleby where he criticized his parents. That was a big book and again, [it] upset the royal family."

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"Harry’s book will cause concern, and it will make headlines around the world, but it won’t destroy the institution," he shared. "And if the institution is so weak that it can’t stand a ghostwritten book by a junior member, then it’s probably not worth keeping it… I mean, quite frankly, a book written by [a monarch], a future queen, Diana, and a book by the future King Charles are far more relevant and important than a book by, what is he now? Sixth in line to the throne? Who will be rapidly going down the hierarchy."

The British author recently wrote a book about Harry’s grandmother titled "The Queen: Her Life." In it, Morton alleged that the late queen met her namesake during the Platinum Jubilee but did not want to be photographed during what was supposed to be a heartfelt moment. At the time, the queen was also faced with mobility issues as her health was deteriorating. 

Andrew Morton posing with his book on Princess Diana

Andrew Morton has written unauthorized books on William, Prince of Wales and Meghan, Duchess of Sussex among others. But he had the cooperation of his subject for the 1992 release "Diana: Her True Story — in Her Own Words," in which Diana acknowledged marital troubles with Prince Charles, now King Charles III. (Chris J Ratcliffe/AFP via Getty Images)

Harry and Markle share two children: Archie, 3, and Lilibet, 1.

"They suggested bringing a photographer with them to take a picture of the meeting between the queen and Lilibet at Windsor Castle," Morton alleged. "Meghan and Harry are always very concerned about the optics, how they look, their image. The queen decided against that because her eyes were bloodshot. And you could also argue that the queen didn’t want what was essentially an intimate family moment to turn into a sideshow. That was always the concern with anything to do with Harry and Meghan, that they would turn it to their advantage, turn it into a three-ring circus."

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The queen passed away on Sept. 8 at age 96.

Queen Elizabeth II sits in her full regal ensemble

Queen Elizabeth II passed away on Sept. 8 at Scotland's Balmoral Castle. She was 96. (Alastair Grant - WPA Pool/Getty Images)

Morton famously teamed up with Harry’s late mother for her 1992 tell-all. Diana turned to Morton after she learned from a friend that the journalist was writing a book about her. The pair used a mutual friend, James Colthurst, as a go-between while they secretly collaborated on the book. In it, Diana acknowledged marital troubles with her husband and his former flame Camilla Parker Bowles, who is now Queen Consort. She described how their relationship torpedoed her marriage behind palace doors. Charles and Diana’s divorce was finalized in 1996 – a year before she died at age 36.

Morton's experience working with the "People’s Princess" is chronicled in the latest season of Netflix’s scripted royal drama "The Crown." It stars Elizabeth Debicki as Diana and Andrew Steele as Morton.

"The most difficult thing to deal with was Prince Charles’ relationship with Camilla," Morton recalled. "When we saw a lawyer, because in Britain the libel laws are very strict, the libel lawyer said to us, ‘How can you say that Prince Charles is having an affair with Camilla Parker Bowles? Are you in the bedroom with them?' And then the next sentence was, ‘Mr. Morton, who do you think a judge would believe, you or the Prince of Wales?' So we told Diana that we couldn’t write about Charles’ relationship with Camilla. And she was furious because obviously, that was something that had really stained her life for the last 10 years."

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Princess Diana and Camilla looking serious

Lady Diana Spencer and Camilla Parker-Bowles at Ludlow Races where Prince Charles is competing, circa 1980. In her 1992 book with Andrew Morton, Diana detailed her unhappy marriage. (Photo by Express Newspapers/Archive Photos)

"She let us read a couple of love letters… and postcards," Morton continued. "And it left no doubt that Charles and Camilla were lovers. And then the lawyer came up with a bright sentence. He said, ‘Their secret relationship upset Diana.’ So you didn’t have to say they were having an affair. So we changed it to, ‘Their secret relationship.’ We put all that, the nature of the relationship with Camilla, in the book. So that’s an example of how difficult it was to get material in the book without attracting a lawsuit."

Morton said that when it came to telling Diana’s story, she was ready to finally set the record straight about her unhappy marriage, which was targeted by tabloids. Shortly before her death, Diana announced that she would "be seeking a more suitable way of combining a meaningful public role, with hopefully, a more private life."

"When it came down to choosing things to go in [the book]… as far as I was concerned, I asked her every question I could think of and put it all in," Morton added.

King Charles and Princess Diana looking serious

Prince Charles and Princess Diana's divorce was finalized in 1996. (Photo by Tim Graham Photo Library via Getty Images)

According to Penguin Random House, Harry’s story will be told with "raw, unflinching honesty" and filled with "insight, revelation, self-examination and hard-won wisdom about the eternal power of love over grief."

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"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," a statement from the publisher read in part. "For Harry, this is his story at last."

The memoir’s title is an apparent reference to "the heir and the spare," a phrase often used to describe royal siblings. Harry’s brother, William, is now Prince of Wales and heir to the British throne. When Harry, 38, was born, he was right behind William, 40, in the line of succession but has since been pushed down. Their father assumed the throne upon the queen's death.

Prince Harry Meghan Markle Oprah Winfrey interview

This image provided by Harpo Productions shows Prince Harry, from left, and Meghan, The Duchess of Sussex, in conversation with Oprah Winfrey. The interview was televised in 2021. (AP)

The Duke and Duchess of Sussex stepped back from royal duties in 2020 and moved to California. Harry told Winfrey, 68, 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.

Penguin Random House’s 2021 announcement included a statement from Harry.

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"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 Associated Press contributed to this report.