The memory of "Granny Diana" is being kept alive for Prince George and Princess Charlotte by their father who regularly talks to them about his mother.
George, who celebrated his fourth birthday on Saturday, and two-year-old Charlotte are growing up with Carole Middleton as their only grandmother.
But Prince William is determined his children should also have Diana in their lives through the stories he tells them about the Princess.
He explained in a TV documentary, Diana, Our Mother: Her Life and Legacy, about how he keeps the memory of his mother alive for his children.
"I think, constantly talking about Granny Diana, so we've got more photos up round the house now of her and we talk about her a bit and stuff.
"It's hard because obviously Catherine didn't know her, she cannot really provide that level of detail."
But William stressed he regularly talks to George and Charlotte about Diana when putting them to bed to remind them "there are two grandmothers in their lives, so it's important they know who she was and that she existed".
Speaking in the documentary, which will be screened in the UK on Monday, William joked about the havoc his mother would have caused at his children's bath times if she was alive.
"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, probably at bath time, cause an amazing ... scene, bubbles everywhere, bath water all over the place, and then leave."
Speaking about the ongoing influence of his mother on his parenting William explained.
"I want to make as much time and effort with Charlotte and George as I can because I realise these early years particularly are crucial for children, having seen what she did for us."
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