Princes William and Harry open up in agonising detail about the enduring scars they bear over the loss of their mother.
And they speak in extraordinary depth about how they coped with unrelenting grief as they made the journey from boys to young men.
While Harry admits crying over his bereavement just twice in 20 years and speaks of his bewilderment that so many strangers were upset, his elder brother recalls the experience as ‘utterly devastating’.
The starkly contrasting effects on the boys may be partly explained by their respective ages at the time of Diana’s death in August 1997. Harry, just 12, was arguably too young to fully comprehend the enormity of what had happened, and said he even came to believe that ‘not having a mum was normal’.
Watching a nation pouring its collective heart out, he candidly recalls wondering: ‘How is it that so many people can be crying and showing more emotion than I actually am feeling?’
Harry spoke earlier this year of ‘shutting down all of my emotions’ for nearly 20 years, and it is hard to imagine what the psychological legacy of that detachment would be on such a young boy.
It makes his recent admission that he came ‘close to a breakdown’ in his late 20s all the more powerfully moving.
William, on the other hand, was 15 and already in the midst of coping with all the issues visited upon any adolescent, let alone one destined to be king. ‘There’s nothing like it in the world, there really isn’t,’ he says in the ITV film. ‘It’s completely and utterly like an earthquake’s just run through the house and through your life and everything.
‘It’s just… your mind is completely split and it took me a while for it to sink in. You know, losing someone so close to you is utterly devastating, especially at that age.
‘I think it really spins you out – you don’t quite know where you are, what you’re doing and what’s going on.’
For both Princes, Diana was a presence long after her death, and William even says of his wedding in 2011: ‘I did really feel like she was there.’
Touchingly, the boys tried to help each other through their darkest hour, though William admits they were ill-equipped for the task. ‘The family came together, and Harry and I tried to talk as best as we could about it, but, being so small at that age, it’s very difficult to communicate or understand your feelings,’ he says. ‘It’s very complicated.’
‘So they always live with you, people you lose, like that. And my mother lives with me every day. I give thanks that I was lucky enough to be her son and that I got to know her for the 15 years that I did.
‘She set us up really well. She gave us the right tools and has prepared us well for life in the best way she could, not, obviously, knowing what was going to happen.’
William says he even felt his mother’s presence at his wedding to Kate at Westminster Abbey in 2011, 30 years after his parents married in 1981.
He recalls: ‘Beforehand I had a lot of time to think about it. When it came to the wedding, I did really feel that she was there… there were times I looked to someone or something for strength – and I very much felt she was there for me.’
At one point, leafing through family photographs with Harry, William observes poignantly: ‘Time spent with her, the feeling of having her around and being loved as a family or as a son, I think those are the most precious special memories to me.’
Harry makes it clear he buried his grief much deeper than his brother, and so finally unearthing it years later was all the more painful. The therapy which he sought at William’s suggestion brought home the enormous emotional burden he had carried as a boy.
‘I was so young. I grew up sort of thinking that not having a mum was normal. 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… make you more sad.’
‘People deal with grief in different ways, and my way of dealing with it was just by basically shutting it out, locking it out. The ten years that I was in the Army, I just dug my head in the sand and it was just… it was just white noise. And I went through a whole period of having to try to sort myself out.’
Harry spells out his pain in extraordinarily intimate detail, explaining how he missed the first and most basic comfort a child can know – the loving hug of a mother.
‘She was our mum, she still is our mum. Of course as a son I would say this, she was, the best mum in the world. To myself and William she was just the best mother ever.
‘She would engulf you and squeeze you as tight as possible – and being as short as I was then, there was no escape, you were there, and you were there for as long as she wanted to hold you. Even talking about it now I can feel the hugs that she used to give us and… I miss that, I miss that feeling. I miss that part of a family, having that mother to be able to give you those hugs and give you that compassion that I think everybody needs.’
Harry says his mother is a constant presence in his thoughts, as she is in William’s – a fact that does little to dull the pain.
‘It has been hard and it will continue to be hard,’ he says.
‘There’s not a day that William and I don’t wish she still was around, and we wonder what kind of a mother she would be now, what kind of a public role she would have, and what a difference she would be making.’
William also reflects on that loss which the Princes share with so many people they encounter.
‘My heart goes out to all the people who have lost loved ones. You know, it does connect you, it’s a very sad club you don’t want to be a member of, but you do all have a shared sort of pain that you can immediately understand and see in anyone when you meet them.’
William sums up Diana’s abiding legacy to her two sons in the film’s closing moments when he says: ‘I think she’d be proud that Harry and I have managed to come through everything that’s happened, having lost her, and that gives me positivity and strength to know that I can face anything the world can throw at me.
‘We felt incredibly loved, Harry and I. I’m very grateful that that love still feels there, even 20 years on. And I think that’s a huge credit to her that I can still feel that love.’