Meghan Markle and Prince Harry's bombshell biography features 'unprecedented' insight, royal expert says

Could Meghan Markle and Prince Harry's life significantly be affected by a new biography? Royal expert Katie Nicholl exclusively talks to ET about Finding Freedom: Harry and Meghan and the Making of a Modern Royal Family, a book coming this summer from royal reporters Omid Scobie and Carolyn Durand. It's reportedly filled with bombshells about the Duke and Duchess of Sussex's life in the spotlight, including "fascinating insight" about their first dates, drama within the royal family, their decision to step down as senior members and their eventual move to America.

Although Nicholl has yet to get her hands on the full copy, she says the excerpts that she's read so far are already telling of what's to come.

"Even Oprah Winfrey wasn't able to get an advance copy of this book. It has literally been kept under lock and key by the Times and The Sunday Times," she explains. "I think it's fair to say this is no Andrew Morton's Diana. However, the level of detail in this book is quite remarkable. What the authors have managed to do is get a level of detail which is unprecedented."

"It's clear that they have spoken to numerous sources," she continues. "There is a lot of speculation that they have spoken to Harry and Meghan themselves, something that the authors have denied, and something the Sussexes' team have been keen to also play down. They say that Meghan and Harry have had no official involvement with this biography, but it's very clear that the authors have had access to sources incredibly close to Meghan and Harry."

Nicholl adds that this book literally "lifts the lid on" when Meghan and Harry's engagement actually took place, which she says happened weeks before it was officially announced by Kensington Palace.

"We get some really remarkable details about those first dates. Just the level of detail, that, for me, has been most impressive," she says. "I think the story is familiar to all of us now, but this is the first time we are really hearing it from Harry and Meghan's perspective, and reading it in its entirety."

"This has made the book compelling and fascinating, but for the royal family, this book has been damaging because it has opened up old wounds," she continues. "I think what's very clear is that Meghan and Harry have wanted to get their side of the story across. This is clearly a couple who feel quite aggrieved by the fact that they've never been able to answer their critics. They have never been able to address incorrect reporting."

Because of that, Nicholl believes this book may be "being used" to correct some of the rumors that were spread by British tabloids over the years.

"To give Meghan and Harry the chance, if not through their own voices, then through the voices of friends, confidants and people that they trust, to get their side of the story out there," she says. "They feel -- Meghan, particularly -- that she has been muted for most of her royal life, as short as it was. She didn't have the opportunity to speak out to address her critics to get her side of events out."

According to excerpts, Finding Freedom also seems to indicate that Prince Harry was unhappy for quite some time. The book claims it was Meghan who gave him the courage to finally break away from the royal family.

"One of the themes that seems to be recurrent in Finding Freedom is that Harry felt very much like a spare wheel," Nicholl explains. "While the media loved this idea of a royal threesome (Kate Middleton, Prince William and Prince Harry), for Harry, he very much felt like a spare wheel. At points [in time], I even heard him complaining that he felt like the gooseberry, the third one along at the date. He never quite fitted in."

"I think that while Kate and William went out of their way to make sure Harry felt like a part of this team, this trio, Harry always wanted to be his own person," she continues. "I think Meghan has very much been the catalyst in giving him that confidence to break free from William and Kate, and to break free from that trio dynamic, which was at times cozy and convenient, but actually wasn't really what he wanted."

Many British tabloids placed the blame on Meghan at the time, alleging that leaving the U.K. was the former Suits star's idea and that she was taking Harry and their now 1-year-old son, Archie, with her to Los Angeles.

"It's my understanding, and this is also explored in Finding Freedom, that it wasn't just Meghan's decision. I think Harry was very much a driving force," says Nicholl. "People don't perhaps give her enough credit. Harry is a pretty opinionated and strong-willed man, and I've been told by several very well-placed sources that it wasn't just Meghan dragging Harry away."

"She gave him a new confidence, but I think the truth is that, for a long while, Prince Harry has wanted out," she adds. "This was a prince who'd spoken quite vocally about the restrictions of being a royal, the weight of burden, a boy who said he wish he hadn't at times been born a prince. I think that says a lot about Prince Harry."