and have spoken of their enduring regret that their last conversation with was a "desperately rushed" phone call.
The Duke of Cambridge and his younger brother, then aged 15 and 12, were in Balmoral with their cousins when Princess Diana died in a car crash in Paris in 1997.
"All I do remember is probably regretting for the rest of my life how short the phone call was," Prince Harry says in an ITV documentary to mark the 20th anniversary of Diana's death.
William said that their last conversation weighed "quite heavily" on his mind, with Harry adding that due to Diana and Prince Charles's divorce, they spent too much time speaking on the phone rather than in person.
"At the time, Harry and I were running around minding our own business, you know, playing with our cousins and having a very good time," William recalled.
"And the phone rang and off he [William] went to go and speak to her sort of for five minutes."
"And I think Harry and I were just in a desperate rush to say goodbye, you know, see you later and we're going to go off. If I'd known now obviously what was going to happen I wouldn't have been so blasé about it and everything else. But that phone call sticks in my mind quite, quite heavily," he said, revealing that he remembered the conversation, but did not want to disclose it.
Prince Harry added: "I can't really necessarily remember what I said, but all I do remember is probably, you know, regretting for the rest of my life how short the phone call was. And if I'd known that that was the last time I was going to speak to my mother the things I would have said to her."
"Looking back on it now, it's incredibly hard. I have to sort of deal with that for the rest of my life.
"Not knowing that that was the last time I was going to speak to my
William and Harry also spoke fondly of their late mother's sense of humor, with Harry saying: "Our mother was a total kid through and through. When everybody says to me 'so she was fun, give us an example' all I can hear is her laugh in my head. One of her mottos to me was, 'you can be as naughty as you want, just don't get caught'. She was one of the naughtiest parents. She would come and watch us play football and, you know, smuggle sweets into our socks."
William revealed that Diana was "very informal and really enjoyed the laughter and the fun." He added that she "loved the rudest cards you could imagine."
"I would be at school and I'd get a card from my mother," he recollected. "Usually she found something, you know, very embarrassing, you know, a very funny card, and then sort of wrote very nice stuff inside. But I dared not open it in case the teachers or anyone else in the class had seen it."
This story originally appeared on Townandcountrymag.com.
* Minor edits have been made by the