It's a story that has played out over the past two seasons of Netflix's The Crown: one in which Princess Diana is overwhelmingly admired compared to her husband, then-Prince Charles. Princess Diana's biographer Andrew Morton, who was also part of the storyline in season 5 of the series released this month, said that the current King found it difficult to accept that Princess Diana was overshadowed by him and found it difficult to accept her popularity.

Morton, who served as a consultant for this season of the show, told Insider, "Diana didn't mind his personal difficulties, but he was overshadowed on the public stage. She was the star of the show and he was not. He couldn't accept that very well. Now he is the star. He is the king."

Known as "The People's Princess," Diana was soon considered more popular than her husband, as evidenced by the couple's 1983 tour of Australia. The public turned out in their thousands to welcome the Prince and Princess of Wales, but it was clear that all most people cared about was seeing Diana.

"The crowd complained when Prince Charles walked by them on his walk," Morton said.

But Prince Charles' second wife, Camilla, had a woman who wanted to be his "cheerleader" and "number two," as Morton told Insider.

"He has known Camilla most of his life." She was like a steady cheerleader who comforted and consoled him, as he had always really wanted someone who could be both his companion and his number two."