Prince William, Prince Harry, Meghan Markle and Kate Middleton
Prince William and Kate Middleton can’t be less popular than Meghan Markle and Prince Harry. Pictured [L-R]: The Duke of Cambridge, Duke of Sussex, Duchess of Sussex and Duchess of Cambridge arrive at Westminster Abbey to attend a service to mark the centenary of the Armistice on Nov. 11, 2018 in central London. Paul Grover/AFP/Getty Images

With a baby due in spring and frequent moments of PDA, Meghan Markle and Prince Harry are dominating the royal spotlight. However, as their increasing popularity takes the focus away from Kate Middleton and Prince William, the couple could be considered a threat to the throne.

Royal biographer Anna Pasternak recently told S Magazine she is worried members of Buckingham Palace’s royal court, referred to as “the men in grey” by Princess Diana, would see the couple as threats that could disrupt the monarchy.

“Meghan is like a grenade that’s been thrown into this archaic system and there are explosions already going on which I think will continue,” she said.

“In a sense, Meghan has rejuvenated the spirit of Wallis and I hope people take the view of her as a kind, witty, loyal and dignified person who unfairly became the most vilified woman in the world,” Pasternak added.

While Meghan’s Hollywood past may make her feel like she was born to shine, the author insisted the former “Suits” star must act accordingly and respect the hierarchy.

“She [Meghan] cannot set the agenda, she has to toe the line and support the monarch and heir. I don’t think she realizes that.”

Instead, Harry and Meghan continue to win favor with audiences across the world that are eager to learn more about the couple. Their popularity takes away the attention that should be on William and Kate, who will one day become the King and Queen.

“I fear if Meghan and Harry’s star rises too high that will be perceived by the courtiers Princess Diana called men in grey as a threat to the heir,” Pasternak explained.

The Palace has not acknowledged Pasternak’s remarks about the “men in grey.”