Prince Harry's comments about Camilla during his press tour for "Spare" were reportedly the "final straw" that led to his and Meghan Markle's eviction from Frogmore Cottage.
Harry, 38, and Markle, 41, were asked to vacate the royal abode so that Prince Andrew could reportedly move in. The process was started Jan. 11, just one day after the Duke of Sussex's memoir was released, according to The Mirror.
One royal expert told Fox News Digital it's not surprising that Harry's comments pushed Charles over the edge.
"The King is ferociously loyal to his wife, so it doesn't surprise me that, above all the things written in ‘Spare,’ Harry's attacks on Camilla were what irked Charles the most," said Chris Andersen, author of "The King."
"As far as the King is concerned, the coronation has as much to do with Camilla as it does with him. Crowning Camilla is the capstone of their love story. But Diana's ghost still hangs over the proceedings. Harry's description of how Camilla schemed to get where she is will make sure of that."
A source told The Mirror Harry's comments about Camilla were the "last straw" and that Harry's memoir crossed a line.
"It was the last straw. Harry was well aware how Camilla would be a red line for his father, and he crossed with flagrant disregard anyway," the source said. "It was the ultimate act of disrespect."
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Prince Harry labeled Camilla a "villain" during his press tour for "Spare." The queen consort was painted as the evil stepmother by the prince in his memoir.
"She was the villain. She was the third person in their marriage," Harry said during an interview with "60 Minutes." "She needed to rehabilitate her image."
"You and your brother both directly asked your dad not to marry Camilla?" Anderson Cooper asked.
"Yes," Prince Harry replied. Cooper went on to ask the royal why.
"We didn't think it was necessary. We thought that it was gonna cause more harm than good and that if he was now with this person, that surely that's enough," he said. "Why go that far when you don't necessarily need to? We wanted him to be happy. And we saw how happy he was with her. So, at the time, it was, 'OK.'"
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Harry also criticized Camilla's relationship with the press.
"That made her dangerous because of the connections that she was forging within the British press. And there was open willingness on both sides to trade of information," Harry said. "And with a family built on hierarchy, and with her on the way to being queen consort, there was gonna be people or bodies left in the street because of that.
"If you are led to believe, as a member of the family, that being on the front page, having positive headlines, positive stories written about you, is going to improve your reputation or increase the chances of you being accepted as monarch by the British public, then that’s what you're gonna do," Harry wrote in "Spare."
"Spare" is Harry’s highly personal and intimate account of his life in the royal family and his relationship with American actor Meghan Markle, Duchess of Sussex.
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Fox News Digital's Ashley Papa and the Associated Press contributed to this report.