Prince Harry "wonders" what kind of mother Diana would be now if she was still alive.
The flame-haired royal tragically lost his mother, Princess Diana of Wales, when he was just 12-years-old and he admits it will always be "difficult" without her in his life.
He said: "It has been hard and it will continue to be hard. There's not a day that William and I don't wish that she was still around, and we wonder what kind of a mother she would be now, and what kind of a public role she would have, and what a difference she would be making. You know, and of course as a son I would say this, she was the best mum in the world."
And Prince William, who was just 15 at the time of Diana's untimely death, thinks about his mother all the time and says she "lives with him every day".
Speaking in the Diana, Our Mother: Her Life and Legacy documentary, William added: "There's not many days that go by that I don't think of her, you know - sometimes sad, sometimes very positively. You know, I have a smile every now and again when someone says something and I think that's exactly what she would have said, or she would have enjoyed that comment. So they always live with you people you lose like that. And my mother lives with me every day."
Meanwhile, William previously revealed Diana would have most likely been a "nightmare grandmother".
He said: "She'd be a nightmare grandmother, absolute nightmare. She'd love the children to bits, but she'd be an absolute nightmare. She'd come and go and she'd come in probably at bath time, cause an amazing ... scene, bubbles everywhere, bathwater all over the place, and then leave."