For years, we've watched as Prince Harry has tried (and often failed) to square his royal duties and responsibilities with the seemingly relentless pursuit of fun and excitement.
It now seems that Diana might, inadvertently, be to blame.
"She was one of the naughtiest parents. She would come and watch us play football and, you know, smuggle sweets into our socks," he says. "One of her mottos to me was: 'You can be as naughty as you want - just don't get caught!'."
Which is all very well when applied to illicit sweets, practical jokes and secret incognito trips out of Kensington Palace for a burger or to the cinema.
But it works less well for a rudderless and reckless teenager for whom 'naughtiness' constitutes under-age drinking, cannabis or (later) naked pool parties in Las Vegas.
When Diana died, Harry was just 12. Life as he knew it was smashed to bits. His mother's death became everybody else's property and he was woefully ill-equipped to deal with it.
Because while William was 15 and becoming aware of his responsibilities and the importance of his role and future, Diana hadn't had time to 'finish' Harry.
"She smothered us with love that's for sure," says Harry. "She would just engulf you and squeeze you as tight as possible. She brought a breath of fresh air to everything that she did."
Diana was one of the "naughtiest parents" to Princes Harry and William, Harry says.
For her cuddly, smiley, gorgeously freckled baby, it had been all hugs and silliness, dressing up, practical jokes and hair-raising drives round country lanes in her Audi convertible with pop music blasting out of the car stereo.
But with Harry, she hadn't got to the duty bit. And then suddenly, she was gone.
First, he had to attend her funeral watched by millions of people across the world on TV. And then there was the astonishing public reaction to his mother's death.
The shock to such a young boy is unimaginable.
Tellingly, while thousands of people who had never met Diana left an ocean of flowers and candles in Kensington Palace Gardens and wept openly in the streets, Harry didn't cry until the funeral cortege reached the island at Althorp, where his mother's body was buried.
Perhaps more distressing, he says he has cried just once for his beloved mother in the 20 years since.
Poor Harry. He was always by far the more emotional and sensitive brother, but for years wouldn't and couldn't talk about her. He has done everything in his power to bottle his churning emotions up and block everything out.
Until recently he couldn't bear to look at any family photos. He will always be haunted by their final conversation on the day she died when he cut it short. It's something he says he will regret for the rest of his life.
"If I'd known that that was the last time I was going to speak to my mother, the things that I would ... the things I would have said to her."
Public duty, like his visit to New Zealand in 2015, wasn't always on Prince Harry's agenda. Photo / Dean Purcell
But saddest of all - particularly given the astonishingly close bond they share - until now, he and his brother never talked about Diana as a mother.
As he puts it himself: "I think it was a classic case of ... don't let yourself think about your mum and the grief and the hurt that comes with it, because it's never going to bring her back and it's only going to make you more sad," he says. "My way of dealing with it was ... by just basically shutting it out, locking it out."
Instead, he rebelled. He partied. He fell out of nightclubs, he wore Nazi fancy dress outfits, he had a drunken wrestle with friends covered in vomit, he was barred from a pub for allegedly calling a barman a 'f****** frog', he hit a photographer... the list goes on and on.
When he was 16, Prince Charles was so worried he arranged for his son to visit an addiction clinic to witness the dangers of drink and drugs. Joining the Army was probably the one thing that kept him sane.
"The 10 years that I was in the Army, I just sort of dug my head in the sand and was just, it was just white noise," he says. "And I went through a whole period of having to try and sort myself out. So there's ... you know, there's a lot of grief that still needs to be..."
But recently - and certainly since meeting and falling in love with his American TV actress girlfriend Meghan Markle - he seems to have turned a corner and is finally addressing his mother's death and the catastrophic impact it had on his life, head on and with enormous courage.
Finally, he has learned how to grieve and to talk about all he has lost in a way that will make any parent weep and forgive him every bit of silliness he's ever committed.
"I can feel the hugs that she used to give us and you know ... I miss that, I miss that feeling, I miss that part of a family, I miss having that mother to be able to give you those hugs and give you that compassion that I think everybody needs."
He describes Diana's love as a love that "even if she was on the other side of a room, that you, as a son, you could feel it.
"She set up us really well. She gave us the right tools."
Some tools, yes, but sadly not all. Because he still occasionally blunders in without thinking.
For example, last month he gave an interview in which he said no one in the Royal Family wanted to be king - a sentiment that must have caused consternation with the Queen and Prince Philip.
