• Andrew Morton compared Princess Diana's and Meghan Markle's early days with the royal family
  • Princess Diana felt low and isolated just like Markle in her first two months with the royals
  • Markle's marriage is better than Princess Diana's because her husband is supportive of her

Meghan Markle and Princess Diana had a similar experience when they just joined the royal family, a royal biographer has claimed.

Andrew Morton, who penned "Meghan: A Hollywood Princess" in 2018, re-released the book with the new title "Meghan and the Unmasking of the Monarchy" Tuesday. The book features new chapters with details about some of Markle's family members and friends, and it also examines the Sussexes' lives behind the palace door. The book is also said to explore the things that led to Prince Harry and Markle's decision to step back from their royal duties.

Morton spoke with Fox News about his book and he weighed in on the striking similarity between Prince Harry's mom and his wife. For him, the late Princess of Wales and the Duchess of Sussex experienced the same thing during the early days of their stay with the royals.

"I was surprised by the parallel between Diana and Meghan, especially in those first two months inside the royal family," Morton told the outlet. "Meghan said she felt low and isolated – Diana felt the same. For Diana, she felt [the palace] was a place of cold energy – a far cry from what felt on the outside. It was astonishing to me."

Morton also pointed out how the two didn't feel supported by the royal family. In a previous interview, the late Princess of Wales felt that she lost herself when she was in the firm.

"The day I walked down the aisle at St. Paul's Cathedral, I felt that my personality was taken away from me, and I was taken over by the royal machine," she said in her BBC interview, as per Insider.

Markle, who was very outspoken before marrying Prince Harry, also said she was silenced. The duchess even deleted all of her personal social media accounts on Twitter, Instagram and Snapchat months before her royal wedding.

According to Morton, Markle was very angry that no one in the palace defended her as the tabloids started to pit her against her sister-in-law, Kate Middleton. The duchess wasn't happy with the news that she made the Duchess of Cambridge cry in the run-up to her royal wedding after a press officer told her that they could not deny or confirm every single story written about the royal family. 

Markle addressed the issue in her interview with Oprah Winfrey that was aired in March on CBS. Markle denied that she made Middleton cry and said it was "the reverse." She also added that "everyone in the institution knew that it was not true."

However, Markle had it easier compared to Princess Diana in some areas because of the support from her husband, Prince Harry. The late Princess of Wales' marriage to Prince Charles was very different.

"Diana spoke about the men in gray who were hostile to her because they were supporters of Prince Charles. And they had problems pretty early on in their marriage. But Meghan and Harry were a double act," Morton said. "And Meghan was seen out and about. Friends of mine used to ring me up and say, ‘I just saw Meghan at such and such.’ She did have a life outside of palace walls and in those early days, she was very popular."

"Meghan and the Unmasking of the Monarchy: A Hollywood Princess" is already out.

Princess Diana, Meghan Markle Princess Diana visited Meghan Markle's school years ago. Wales arrives at her London health club on Nov. 20. (R) Meghan, Duchess of Sussex departs the Bristol Old Vic on February 01, 2019 in Bristol, England Photo: Getty Images/Johnny Eggitt, Chris Jackson