Duke of Cambridge and Prince Harry reveal last phone call with mother 20 years after Princess Diana's death

Brothers say they last spoke to mother in a brief phone call on the day she died

An undated handout picture released by Kensington Palace from the personal photo album of the late Diana, Princess of Wales shows her embracing Prince Harry while on holiday at an undisclosed location (Kensington Palace)

The Duke of Cambridge and Prince Harry have revealed details of the final conversation they had with their mother almost 20 years after her death.

Their final words with her were exchanged in a brief phone call on the day she died that now weighs heavily on William’s mind, he said in a new interview.

In a documentary about Diana, Princess of Wales, the brothers speak of their lasting regret at how short their final chat with their mother was, with Harry confessing it is something he will regret “for the rest of my life”.

William was 15 and Harry 12 when their 36-year-old mother was killed in a car crash in Paris on 31 August 1997, with the image of the two young princes walking behind their mother’s coffin at her funeral one of the most enduring of the 20th century.

But looking back at the life of the princess, whose death 20 years ago shocked the world, Harry, now aged 32, said “to myself and William she was just the best mother ever” who “brought a breath of fresh air to everything she did”.

In the programme documenting Diana’s personal journey, her campaigns supporting the homeless, Aids victims, and banning landmines, and her death, Harry reveals he has cried just twice for his mother – once at her funeral and on another occasion that he would not disclose.

Diana with her sons in April 1992 (PA)

William – who at 35 is now just a year younger than Diana was when she died – described the “very good time” they were having at Balmoral, the Queen’s private Scottish home, where the royal brothers were playing with their cousins when their mother called.

William, interviewed with his brother at Kensington Place for the ITV documentary, said he spoke to his mother first.

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

“But that phone call sticks in my mind, quite heavily.”

Asked if he remembers what his mother said, William replied “I do”, but did not disclose details of the conversation.

Harry then took his turn to talk to their mother.

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

A picture from Diana’s personal photo album of her William. She was pregnant with Harry (Kensington Palace)

“Looking back on it now, it’s incredibly hard, I’ll have to sort of deal with that for the rest of my life. Not knowing that was the last time I was going to speak to my mum, how differently that conversation would have panned out if I’d had even the slightest inkling her life was going to be taken that night.”

On what would have been Diana’s 56th birthday, 1 July, William, Kate and Harry, joined by Prince George and Princess Charlotte, attended a service to rededicate her grave at her childhood home, Althorp House, where she was buried on an island.

Harry, who has spoken publicly about his own mental health battles, said: ”The first time I cried was at the funeral on the island and probably only since then maybe once. So there’s a lot of grief that still needs to be let out.“

Diana’s vey public marriage break-up with Prince Charles was a defining moment in her life, and the documentary features the moment when, in December 1992, the then-Prime Minister John Major announced to the Commons the couple had agreed to separate.

Previously unseen family photos of the royal brothers taken by their mother are shown in the programme with William and Harry filmed trawling through the albums compiled by their mother.

In lighter moments, they discuss her sense of humour with Harry saying: “Our mother was a total kid through and through, when everybody says to me ‘so she was fun, give us an example’, all I can hear is her laugh in my head.”

Reflecting on the 20 years since his mother’s death, Harry said: “It has been hard and it will continue to be hard, there’s not a day William and I don’t wish that she was still around and we wonder what kind of mother she would be now, and what kind of a public role she would have and what a difference she would be making.”

Diana never saw her work to help outlaw landmines come to fruition as she died before the international treaty to ban the military weapons was signed.

But Harry described how he found letters on the subject dated the day of her death, but never sent: “About a month ago I found a whole series of letters. Letters that she was supposed to top and tail that were dated 31st of August that were sitting on her desk here.

“She knew exactly what needed to be done, she was writing letters to certain people to say ‘right, this is what needs to happen in order for this whole tidal wave to change.”

The documentary, Diana, Our Mother: Her Life and Legacy will be screened on ITV on Monday at 9pm.

Press Association