Prince William and Harry's relationship is "on absolute ice" just days ahead of the King's Coronation, it has been claimed.
Both princes will be at Westminster Abbey on Saturday to see Charles and Camilla crowned after Harry confirmed his attendance.
It will see him and William together in a public setting for the first time since he lambasted the royals in his memoir, Spare.
In the book, the Prince of Wales came in for some of the fiercest criticism from his younger sibling, who claimed they once had a physical altercation.
Despite them both set to be at this week's historic event, royal biographer Tina Brown doubts there will be any reconciliation between the two brothers.
She told LBC's Andrew Marr: "They are totally estranged. I do not think there will be any contact between them at the Coronation. I think that their relationship right now is on absolute ice.
"The longer Harry dwells on what happened in his life, the more he feels resentment against William, because he feels, I think, that William was even more calculated, essentially, in making him number two, making him the spare, and feel like the spare at all times.
"So, there's no contact between them, I'm told. I think Charles wants to have some kind of rapprochement. But I think it's going to take years… It never happened between George VI and the Duke of Windsor, it just got worse.
"Alienations tend to get worse as time goes by, rather than better."
It comes after it emerged that Harry will come to the UK on a flying visit for the Coronation - but his wife Meghan will stay in California with their two children, Prince Archie and Princess Lilibet.
This means he will skip the King’s Coronation concert on May 7 to fly back home and celebrate Archie's fourth birthday.
A royal source previously said: "After much back and forth, Harry said that he would be returning for the King’s Coronation but it will only be a fleeting visit.
"Organisers have been told Harry won’t be attending the concert with the rest of the Royal Family, which is a great shame as it will be such a spectacular event."
Meanwhile, organisers are said to be in the dark about the Duke of Sussex’s plans, with the big event less than one week away.
They reportedly don’t know when he’ll arrive, where he’s staying or if he’s happy with where he’ll be sitting in the Abbey, reported the Mail on Sunday.
One source told the Mail on Sunday: "He has not been responding other than in a 'We acknowledge your email'' holding manner.
"It's like trying to communicate with Mars – it was easier to deal with Sinn Fein."
The comment comes in reference to Michelle O’Neill, Sinn Fein’s vice president and leader in Northern Ireland, who accepted an invitation to the Coronation.
The source reportedly added: “Harry seems to be adopting a High Noon approach, making everyone sweat about his movements.
"While the Royals are confident that he will show up, others involved are not quite so convinced."