Kate Middleton Helped Heal Prince William and King Charles' 'Frosty' Relationship

Kate Middleton is the glue that keeps the royal family together, and a new book reveals the Princess of Wales helped heal Prince William and King Charles' relationship.

"There were moments when the relationship between the king and the Prince of Wales was frosty,” royal expert Robert Jobson told an outlet while promoting his new book, Catherine, the Princess of Wales. “There have been problems like that in the past.”

According to Jobson, the mom-of-three is “the hub, the conduit to good relations" between William and Charles.

Charles and Kate have developed a unique bond over the years, and the princess is often seen as the monarchy's secret weapon.

“She’s been brilliant. I think the king absolutely adores her,” Jobson added. “You can see his eyes light up when he sees her.”

The author noted that His Majesty views Kate as “the daughter he never had.”

"Navigating such tricky flare-ups between her husband and her father-in-law has put the princess in an invidious position over the years,” Jobson wrote in his biography. “She has learned to tread carefully on occasion and let time heal.”

Jobson noted that Kate is “always loyal” to William, but she is “a pragmatic ally” for Charles.

The commentator later explained that the brunette beauty is “an arbiter and a mediator” between the father and son. “She’d keep their counsel, and I think that they trust her," he continued. "The king trusts her implicitly.”

The future queen has shown her commitment to The Crown and her in-laws over the years, and Charles will formally recognize her contributions by appointing Kate as a member of his Privy Council.

“It will mean, as the future Queen, she will be able to attend the Accession Council, the ceremonial body that assembles upon the monarch’s death to proclaim the accession of a successor,” Jobson penned. “And therefore, be in the room at St James’s Palace when William becomes King.”

"He gave her a promotion in the Royal Victoria Order, which is an ancient order that was basically thanking her for the work that she’s done,” he explained. “But at some stage going forward, she’ll be made a member of the Privy Council so that she can be present when William is made King.”

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OK! previously reported Charles and Kate's closeness was on full display at Trooping the Colour, as it was Kate's first public engagement in six months due to her cancer diagnosis.

“The protocol is that traditionally Kate and William would be standing next to each other and the King and Camilla standing next to each other," Grant Harrold said on behalf of Slingo. "It is planned but it is also changing the protocol to show the King and Kate united with each other and going through similar battles, so I would say this is down to the King’s preference. The balcony is all orchestrated, but I have a feeling the King said to Kate, ‘You stand next to me.'"

Kate and Charles are undergoing treatment simultaneously, and the princess' balcony appearance wowed royal watchers.

“It was nice that Charles and Catherine were standing next to each other, they are very close and it showed they are supporting each other," the former royal butler continued. "I think it was a nice gesture and I’m sure William is pleased they were there beside each other."

Jobson spoke to Us Weekly.