Camilla Parker Bowles managed to calm Prince Charles down during his tedious diary meetings. The Duchess of Cornwall was dubbed as a secret weapon by a royal expert.

In the book “The Duchess: The Untold Story,” royal author Penny Junor discussed the lives of Camilla and Prince Charles behind the scenes. She said that at the beginning of the royal couple’s relationship, Prince Charles’ staff was still wary about Camilla because some of them were still loyal to the late Princess Diana.

But it didn’t take Prince Charles’ staff to realize that unlike Prince Charles and Princess Diana’s acrimonious working relationship, Camilla actually had a civilizing influence on the future king. And as such, she became their secret weapon. “The diary meetings were always a painful process,” Junor said.

The royal author said that Prince Charles was always hot, so the windows inside the meeting room were also flung open. Camilla was the one who encouraged him to keep the windows shut so that his staff would have an easier time during their meetings.

And with Camilla around, Prince Charles also tended to behave better. When his wife wasn’t there, the future king could kick off instantly. And when she was, Prince Charles seemed to be calmer, warmer and a bit more civilized.

Prince Charles and Camilla tied the knot in a civil ceremony in 2005. At that time, Princess Diana’s supporters still disliked Camilla. While Prince Charles was still married to Princess Diana, he had an affair with Camilla, and it became widely publicized after the late Princess of Wales confirmed it during an interview.

While speaking with Martin Bashir for Panorama, Princess Diana said that there were three of them in her marriage to Prince Charles. The mom of two also said that she had been aware that Prince Charles was having an affair but still pushed through with their marriage because of love.

Princess Diana passed away following a fatal car crash in Paris on Aug. 31, 1997.

Prince Charles and Camilla Prince Charles, Prince of Wales, and Camilla, Duchess of Cornwall, attend the opening of a new terminal at the Owen Roberts International Airport on March 27, 2019, in George Town, Cayman Islands. Phil Noble - Pool/Getty Images