Prince William is "going to be furious" at brother Prince Harry over his book, Spare, a Royal correspondent has claimed.
The guest on Good Morning Britain also added that Harry's attendance at his father King Charles' coronation later this year will likely "be a joint decision", meaning that William could ban him from the event.
Chief Royal Correspondent for Newsweek Jack Royston told GMB hosts Ben Shephard and Kate Garraway that it will likely be up to King Charles, and possibly Camilla, Queen Consort, as to whether Harry and wife Meghan Markle will be invited - amid their estrangement from the Royal Family.
While it could ultimately be up to the Duke of Sussex if he attends or not, the Royal correspondent added that Prince William may have a say in if he is invited to the event.
The Prince of Wales' wife Kate Middleton, Princess of Wales, could also have a say he suggested - as Harry confessed he wasn't sure if he would be going, in an interview for ITV with Tom Bradby set to air on Sunday.
Speaking on GMB on Friday ahead of the tell-all interview, and the release of Harry's bombshell memoir next week, Jack spoke of who would decide if Harry was welcome or not.
He said that William "will be furious" with his brother for what is revealed in the book and on TV, and addressed whether there was a way back for Harry and wife Meghan.
In the past few days, extracts from the book have been leaked - while clips have been released from both his interview with Tom, and his US interview on GMA with host Michael Strahan.
The latest clips from his chat with ITV presenter Tom have seen Harry discuss past drug use, him seeing a "red mist" in brother William and his hopes to have his father and brother back in his life.
He also said "staying silent won't help" after hitting back at his family for "briefing stories to the press", and he denied "invading their privacy" with his tell-all book.
Meanwhile, an extract from the book leaked ahead of its release saw Harry claim he was attacked by William during a row in 2019.
The book also touches on his reaction to his father King Charles not allowing wife Meghan to be at Balmoral when the Queen died, saying it was "disrespectful" and his reasons for it didn't make sense.
GMB guest Jack said of the book: "This is definitely the most intimate and most private account we have ever had of any Royal Family member in history. There is stuff in this book that deserves attention."
Host Kate then said of the bombshells: "It makes you wonder if they will look back and think actually, there was a reason why not speaking out has been in place for so long."
On the coronation, Jack went on: "It's obviously not completely up to him whether he attends the coronation, he needs an invite. He can't turn up as a kind of bystander, a hanger-on and just stand in the mall with everyone else, so he's got to have an invite.
"Obviously William is going to be furious about everything that Harry has put in this book and I actually have some sympathy for Harry in relation to that relationship.
"But William will be furious and I cannot see William wanting Harry at the coronation, after everything that has been said."
Host Ben asked: "Does William have the power to say to his dad I don't want Harry there?"
Jack went on: "I think it is a decision that will be made jointly. Charles is obviously the King and the Prince of Wales does not trump the King.
"But William is Charles' son, Charles and Camilla are both mentioned as well. I think this will be discussed by the three of them together and probably Kate as well.
"But William's voice does count in that conversation. He doesn't trump the King but his voice counts."
Good Morning Britain airs weekdays at 6am on ITV1 and ITVX.
