When Prince Harry and Duchess Meghan joined Prince William and Princess Kate for a royal walkabout outside the gates of Windsor Castle following the death of the Queen, it was seen as a brief show of royal unity during a difficult time.

According to an upcoming book, however, the whole thing was a sham that was uncomfortable for everyone involved, particularly Kate.

In his new book Our King: Charles III: The Man and the Monarch Revealed, reports the Daily Mail, author Robert Jobson writes that “sources close to the royal family” told him that the demonstration of unity was an “illusion.”

READ MORE: Source: ‘Both Couples Found It Hard’ During ‘Awkward’ Windsor Castle Walkabout Following The Queen’s Death

“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’d ever had to do,” Jobson writes.

The book takes an inside look at the war being waged by the Duke and Duchess of Sussex against the rest of the royals, tracing how it began and the still-ongoing fallout.

Among the revelations Jobson claims are then-Prince Charles’ frustration when Harry issued a statement confirming his relationship with Meghan Markle in the midst of his 2016 Gulf tour, griping about Harry’s “bad manners” for stealing the spotlight

READ MORE: Prince Harry And Meghan Markle ‘On Brink Of Making Decision’ About Attending King Charles’ Coronation, Source Says

Jobson also writes that the Queen grew “tired” of Harry and Meghan’s constant complaining, and described their behaviour as being “quite mad.” She also felt that Harry had become “so consumed” with his wife that it was “clouding his judgement.”

In addition, Jobson claims that the tipping point was the Sussexes’ bombshell interview with Oprah Winfrey in March 2021, which led Charles and William to believe Harry was a loose cannon who could no longer be treated as a trusted member of the family.

Another revelation in Jobson’s book, reports the Mirror, involves the so-called “Sandringham Summit” in January 2020, in which the Queen chaired a family meeting to hash out the terms of Harry and Meghan’s exit after their announcement they would no longer be working royals.

READ MORE: Prince Harry Says He Felt ‘Stuck In This World’ Before Meghan Markle ‘Saved Me’

According to Jobson, the Queen was so concerned about leaks emerging from the meeting that she had the room swept for listening devices, even refusing to allow Meghan to attend via video link due to fears of a security breach.

Jobson also writes of Megan being invited for a one-on-one chat with the Queen, who told her she was delighted that her grandson had “finally found love.” When the Queen advised her to spend some time with Prince Edward’s wife, Sophie of Wessex, to learn the royal ropes, as it were, the Queen was taken aback by Meghan’s curt three-word reply: “I’ve got Harry.”

READ MORE: King Charles III Made Decision To Evict Prince Harry And Meghan Markle From Frogmore Cottage After Camilla ‘Spare’ Attacks, Sources Say

Our King: Charles III: The Man and the Monarch Revealed hits bookshelves on April 13.