The author of an upcoming book about the royal family has said he did not interview the Duchess of Sussex for it but shares mutual friends with her which helped with sourcing information.

Omid Scobie’s book, Endgame, is set to be released on Tuesday and will look “inside” the royal family and the monarchy’s “fight for survival”.

The 42-year-old, who previously co-authored a biography of the Sussexes, insisted in an interview with The Times that he was “not her (Meghan’s) friend”.

“I have mutual friends with (Meghan), and that definitely helps with getting information and breaking details,” he told the newspaper.

Harry and Meghan are said in the book to be “in a good place”.

The book makes a series of claims about the royals and asserts that the future of the royal family is “in a crisis”, as revealed in The Times article.

“That crisis being a lack of interest from young people, an apathy, a growing republican movement, questions over whether the family still uphold the morals and values of the crown that the Queen did such a great job of,” Scobie said.

Among the claims made in the book are that there is a rift between the King and the Prince of Wales, that the Queen has “quietly thanked” Piers Morgan for “defending the Firm” and that a timid Princess of Wales has to be encouraged to perform engagements.

The Times also reported Scobie’s book making a series of claims involving the Sussexes – including that William was involved in “things that have gone out about his own brother”, that the elder brother ignored texts from Harry when the family were making their way to Balmoral before the late Queen died last year and that Charles and Meghan exchanged letters in the wake of her interview with Oprah Winfrey.

Prince and Princess of Wales
Scobie’s book made claims the Prince of Wales ignored texts from his brother when they were heading to Balmoral before the late Queen died (Chris Jackson/PA)

The alleged letters are said to reveal the identity of two people the Duchess claimed, in the TV interview, aired “concerns” about the colour of then-unborn Prince Archie’s skin, The Times reported.

According to the newspaper, the book also claims Meghan sends the King photos of Archie and Princess Lilibet and that she and Harry recorded a video of them singing Happy Birthday for their grandfather this month.

Buckingham Palace declined to comment on the extracts from Scobie’s book.

The author also spoke to The Times on more personal matters, telling the newspaper of the abuse he receives from “anti-Meghan social media trolls”.

“I’ve really struggled with it, to be honest,” he said. “I definitely felt at times like I wanted to just disappear.”