Princes William and Harry have opened up about their mother Princess Diana for the first time in an intimate documentary 20 years after her death.

Prince William and Harry have opened up about their mother together for the first time in a new documentary commemorating 20 years since her death.

Reminiscing about their mum Princess Diana, who died at the age of 36 in a car accident, the brothers flick through a family album remembering her ‘naughty’ ways and how she “smothered them with love”.

Opening up about the 20-years of relative silence talking about their mother together, Harry says: “This is the first time the two of us have ever spoken about her as a mother.

“She was very informal and really enjoyed laughter and the fun. She was one of the naughtiest parents”.

Speaking about Diana’s life as part of the Royal family, William commented on his mother’s understanding of life “outside the palace walls”.

He adds: “But she understood there was a real life outside the palace walls.”

Harry comments: “She was our mum. She still is our mum and of course, as a son I would say this, she was the best mum in the world.

“She smothered us with love, that’s for sure.”

The latest ITV documentary, Diana, Our mother: Her Life and Legacy, will air later this month.

Jo Clinton-Davis, Controller of Factual at the service said: “This new ITV film will offer viewers a fresh and revealing insight into Princess Diana through the personal and intimate reflections of her two sons and of her friends and family, many of whom have never spoken before, to bring together a definitive portrait of a unique person who touched the lives of millions.”