There was a time when the bond between the two princes was so strong that Prince Harry felt his older brother was the only person in the world that he could really trust.

Talking to me while I was writing his biography, Harry said his relationship with William had been the most important in his life. They disagreed on lots of things, he told me, but if they ever argued they would always find a way to make up and get on with things. They were a team. It’s terribly sad to think that it was just over three years ago when we had that conversation. Since then, so much has changed, not least the closeness the two brothers once shared, which seems to have shattered.

They now live entirely separate lives and not just because there is an ocean between them. I fear the news that the Sussexes and Cambridges did not see each other on Harry and Meghan’s surprise trip to the UK – their arrival coming while William and Kate are said to be out of the country skiing – is a sign of how the land lies.

Their unique closeness was born of having been through so much at such a young age. Much has been written about how traumatising it must have been for the pair walking behind their mother’s coffin in 1997. For William and Harry, it was the hardest thing they’d ever had to do. Nothing about their mother’s death was private. The whole world was watching them, and the horror of it all drew them closer.

Strange childhood

Even aside from the death of Diana, Princess of Wales, though, theirs was a strange childhood – one which no one else could understand.

Harry told me how difficult it was for both of them growing up to trust people and truly relax. They never knew, he said, if the people clamouring to be their friends only liked them because of who they were.

Growing up, they took different paths but stayed as close as ever. When Catherine came onto the scene, Harry said she was like the sister he’d always wanted. The three of them were thick as thieves. 

William always looked after Harry, he was always there for him and wanted the best for him, which is why he was so hurt when Harry and Meghan went after Catherine in their Oprah Winfrey interview. Loyalty is important to William – monarchy, too.

He doesn’t believe in betraying the family like that. He was angry, too, about how rude Harry was about their father. When Harry said that he had tried to help his “trapped” brother, I imagine that must have cut very deep.

And the wounds from the past couple of years don’t appear to be healing with any great speed.

It’s the children I feel saddest for – they are very good for repairing rifts and forcing a sunnier atmosphere when things have turned cold between adults.

But Lilibet has never even met her cousins. It seems a terrible shame not to all get together as two young families, apologise for all that has happened between them and move on. I only hope they find a way to meet in the middle.

Angela Levin is a journalist and royal biographer