Kate Middleton said the walkabout alongside Prince Harry and Meghan Markle after Queen Elizabeth's death was 'one of the hardest things she's ever had to do,' per a new royal book

• Kate Middleton said a September 2022 walkabout was difficult, per a royal book.
• Robert Jobson's book details Kate's reported feelings in an excerpt published in the Daily Mail Friday.

In an excerpt of his book "Our King Charles III: The Man and the Monarch Revealed" published Friday in the Daily Mail, Robert Jobson details Kate Middleton's feelings toward the walkabout she took with Prince William, Prince Harry, and Meghan Markle after Queen Elizabeth's death in September 2022.

"Catherine later admitted to a senior royal that, such was the ill feeling between the two couples, the joint walkabout was one of the hardest things she's ever had to do," Jobson, the Evening Standard's royal editor, writes in his book.

According to the author, sources close to the royal family confirmed the act of unity was "all an illusion."

The walkabout occurred months before Prince Harry published his tell-all memoir "Spare" and the release of the Netflix documentary "Harry & Meghan."

"If Catherine found it almost unbearable before all this to share a walkabout with the Duke and Duchess of Sussex, then how — one has to wonder — do she and William feel about them now?" Jobson wrote in the excerpt.

The Prince and Princess of Wales did not immediately respond to Insider's request for comment.

Jobson also wrote that the Queen was tired of Harry's "mad" behavior in the months leading up to her death.

"At that point, the Queen was frankly mystified by the couple's behaviour, describing it as 'quite mad.' She came to believe, however, that her grandson was 'so consumed' by his love for his wife that it was 'clouding his judgment,'" Jobson wrote.

Harry's relationship with King Charles and Prince William has been strained for years, Jobson details. The royal author believes tensions began when Harry released a formal statement telling the press and online trolls to stop harassing Meghan. The statement was released in November 2016 without Charles or William's knowledge.

The incident was detailed in the documentary "Harry & Meghan," where the duo discussed the details leading up to their decision to step back from royal life. Since the release of "Spare" in January, Harry's relationship with the royal family has been "torn to shreds," Us Weekly reports.

Jobson's book is set to release on April 13.