Prince William was just 15 when his mother Princess Diana died. But her influence continues to shape his life to this very day.

William has spoken on a number of occasions about the loss of his mother, who was tragically killed at the age of 36 in a car crash in Paris. And she was at the forefront of his mind when he revisited one of the most impactful moments of his childhood in a recent documentary.

In the show, titled Prince William: We Can End Homelessness, William reflected on how his mother Diana first introduced him to the issue of homelessness by taking him and Harry to The Passage, a UK charity supporting those experiencing or at risk of homelessness, when he was 11.

And he shared a touching memory about watching his mum interact with those around them. “My mother went about her usual way, making everyone feel relaxed, having a laugh and joking with everyone,” he recalled. “I remember at the time kind of thinking, ‘Well, if everyone doesn’t have a home, they’re all going to be really sad.’ But it was incredible how happy an environment it was.”

Reflecting further on the experience, William continued, “I remember having some good conversations, playing chess, chatting and that’s when it dawned on me that there were other people out there who don’t have the same life as you do. You know, when you’re quite small, you just think life is what you see in front of you and you don’t really have concept to look elsewhere. It’s when you meet people, as I did then, who put a different perspective in your head and say, ‘Well, I was living on the street last night,’ and you’re like, ‘Woah.’ I remember that happening.”

The Passage was founded in 1980 to provide practical support and a wide range of services to help transform the lives of homeless people. Since his first visit with his mother, William has returned on a number of occasions to show his support for the charity; in 2009, he slept rough for a night with Centrepoint to better understand the plight of those without a roof over their heads.

Ending homelessness is an issue close to William’s heart, not least because his late mother was such a champion of the cause. Princess Diana also raised her sons to understand how fortunate life their life behind the palace walls was – and it’s a message William is now passing on to his own children, Prince George, Princess Charlotte, and Prince Louis.

“I am starting to introduce homelessness to my children on the school run. The first few times I thought, ‘Do I bring this up or should I wait to see if anybody noticed?’ Sure enough they did and they were just sort-of silent,” he said. “After I said what was going on, I could see their brains try to work out what that means. I do think it’s really important that we start those conversations when the children are small so they’re not just living, you know, in their own little worlds.”