A trailer for Diana, Our Mother: Her Life and Legacy was released in the UK overnight, marking the first time Prince William and Prince Harry have spoken together publically about their late mother.
The moving documentary – in honour of the 20th anniversary of Diana’s death – shows the princes looking through an album of family photographs.
This is the first time that the two of us have ever spoken about her as a mother,” Prince Harry states.
“She was very informal, and really enjoyed the laughter and the fun,” Prince William adds.
“She was one of the naughtiest parents. But she understood there was a real life outside of the palace walls.”
“She was our mum. She still is our mum,” he continues.
“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.”
In the trailer the two royals can be seen looking at a picture of Diana with a young Prince William.
“Believe it or not, you and I are both in this photograph, you’re in the tummy,” William tells his brother.
ITV’s Jo Clinton-Davis 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.”
The documentary is set to air later this month.