New pictures and footage of Princess Diana with her sons has been released.

A new documentary to mark the 20^th anniversary of Princess Diana’s death will give even greater insight into her life as a mother. The Duke of Cambridge and Prince Harry are said to have given their most honest interview ever and say they won’t be doing it again. “Harry and I feel very strongly that we want to celebrate her life, and this is a tribute from her sons to her,” William says of the anniversary documentary.

The Duke on the 20th anniversary year: "It feels like a good time to remember all the good things about her." pic.twitter.com/Nu338JbBLY

— Kensington Palace (@KensingtonRoyal) July 23, 2017

Pictures from Diana’s personal photo albums will be shared in the ITV special, Diana, Our Mother: Her Life and Legacy, as well as family footage of the late Princess with her sons. Kensington Palace has released a few short clips from the documentary which sees Harry call his mother “one of the naughtiest parents”.

Watch TRH share some of their favourite memories of their late mother.

Prince Harry: "She was one of the naughtiest parents!" pic.twitter.com/zKIcZbe4rf — Kensington Palace (@KensingtonRoyal) July 23, 2017

The official Twitter page for William and Harry also released never before seen pictures of the young princes with their mother.

The Duke and Prince Harry are pleased to share 3 photographs from the personal photo album of the late Diana, Princess of Wales. pic.twitter.com/mUhzQB08TV

— Kensington Palace (@KensingtonRoyal) July 23, 2017

William also reveals his regret over his final conversation with his mother in the interview. Explaining that he and Harry were at their Grandmother’s home playing with their cousins, William says his rushed conversation with his mother weighs “quite heavily” on his mind.

“Harry and I were in a desperate rush to say goodbye, you know ‘see you later’… If I’d known now obviously what was going to happen, I wouldn’t have been so blasé about it and everything else.”

Harry also spoke about the last time he spoke with his mother, saying:

“It was her speaking from Paris, I can’t really remember what I said but all I do remember is probably regretting for the rest of my life how short the phone call was.”

Diana, Our Mother: Her Life and Legacy will air at 9pm on Monday on ITV.