Prince Harry jetted from Los Angeles to London a week before the grand statue unveiling at Kensington Palace, where he lived most of his life and Prince William remains with his young family.
But instead of staying at the ancestral home, he instead opted to stay at Frogmore with his cousin Princess Eugenie.
Palace insiders say he quickly became a “right royal pain in the behind”.
“It was hard enough for aides to organise this tribute to Princess Diana with her sons barely on speaking terms.
"But Harry made it even more difficult than it had to be,” says a source.
“He wouldn’t go to rehearsals, he refused to share the details of his speech in advance, and basically made everyone very nervous. William was spitting venom.”
The source says headlines surfacing in the London press late last month claiming Wills refers to Harry’s wife, Duchess Meghan, as “that bloody woman” did little to promote harmony between the brothers.
The Duke of Sussex, 36, reportedly still holds a grudge about William blithely advising he “take as much time as you need to get to know this girl” before he proposed in 2017.
“Harry was already nervous about coming home again. So walking into a fresh barrage of insults directed at his wife immediately put him on the back foot. Harry has an ego on him the size of California so when that happened, there was no way he’d back down.”
William is also said to be disgusted by new rumours Harry and Meghan, 39, have compiled a 30-page dossier to “justify” their treatment of Kensington Palace staff.
It is part of an external investigation of alleged bullying from the pair before they left the royal family.
“Imagine if the boot was on the other foot and William and Catherine tried to ‘justify’ all the allegations Harry and Meghan have publicly made against the palace … The backlash out of their camp would be unsurvivable,” says an insider.
“It’s their hypocrisy that bothers William the most – which was probably relayed to Harry in no uncertain terms.”
WATCH BELOW: Prince Harry and Prince William unveil the new Princess Diana statue on her 60th birthday. Post continues after video...
Despite earlier reports that Harry was “remorseful” over his repeated public attacks on the family, our sources say all feeling of goodwill vanished the second he touched down at Heathrow Airport.
The private confrontation between him and 39-year-old William “went nuclear”.
“Neither brother thinks they are in the wrong, and both are headstrong, emotional, and proud – it’s a bad combination,” says a source.
“No-one knows exactly what was said, but it’s clear there’s zero chance of them coming back from it now.
“It’s such a shame, given this all happened when they were meant to be honouring Diana – who would be upset about all of this.”
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