What haunts Prince Harry most about the death of his mother, Princess Diana

"Instead of helping, the photographers carried on taking photographs of her dying" - Prince Harry

The princes William and Harry with (L to R) their grandfather, Prince Philip, their uncle, Earl Spencer, and their father, Prince Charles in the funeral cortege for Diana, Princess of Wales, on September 6, 1997. The Princess died on August 31, 1997 in a car accident in Paris. Jeff J. Mitchell / RTA/WPA Pool / AFPShow less

Prince Harry has spoken of his anguish at discovering photographers took pictures of his mother, Princess Diana, as she lay dying in the aftermath of the car crash that killed her.

"I think one of the hardest things to come to terms with is the fact that the people that chased her through into the tunnel were the same people that were taking photographs of her, while she was still dying on the back seat of the car,” he said. "William and I know that, we've been told that numerous times by people that know that was the case.”

Harry added: "She'd had quite a severe head injury, but she was very much still alive on the back seat, and those people that caused the accident, instead of helping, were taking photographs of her dying on the back seat. And then those photographs made their way back to news desks in this country."

But the prince, who was only 12 when he lost his mother, said he was glad to be part of her funeral cortege.

The fifth-in-line to the British throne had previously said that “no child” should have been asked to walk behind their parent’s coffin in front of hundreds of thousands of people. But in a 90-minute film to be aired on the BBC on Sunday to mark 20 years since Diana's  death, Harry, now 32, spoke about how it was decided that he and his older brother Prince William would  join the funeral procession.

He said: “I think it was a group decision. Before I knew it, I found myself in a situation with a suit on and a black tie, a white shirt, I think, and I was part of it. Generally, I don’t have an opinion on whether that was right or wrong. I am glad I was part of it. Looking back on it now I am very glad I was part of it.”

William, who was 15 at the time, added that walking behind the coffin was “one of the hardest things” he ever had to do.

He described the difficulties of being a prince and having to carry out his duties in that role while coming to terms with the loss.

“It was that balance between duty and family and that was what we had to do. I think the hardest thing was that walk. It was a very long, lonely walk,” the 35-year-old prince recalled. “But then again, [there was]the balance between me being Prince William and having to do my bit versus private William who just wanted to just go into a room and cry [having] just lost his mother.”

Walking with William and Harry were their maternal uncle, Earl Spencer, their grandfather, Prince Philip, and their father, Prince Charles. The procession lasted nearly two hours.

In the documentary, the princes revealed it was their father Charles who broke the news of their mother’s death while they were staying at Balmoral Castle, the royal family's holiday home in Scotland.

“One of the hardest things for a parent to have to do is to tell your children that your other parent has died,” Harry said. “How do you deal with that, I don’t know. But he was one out of two left. And he tried to do his best to make sure we were protected and looked after. He was going through the same grieving process as well.”

The brothers praised their grandmother, Queen Elizabeth II, who was also present in Balmoral, for protecting them during their grieving period.

The Queen was criticised at the time for an apparent lack of compassion at the news. She stayed in Balmoral in the aftermath and made no public pronouncement about her former daughter-in-law’s death for five days.

However, William said he was grateful that his grandmother had shielded him and Harry from the outpouring of grief in the press and in the public.

“At the time, you know, my grandmother wanted to protect her two grandsons, and my father as well. Our grandmother deliberately removed the newspapers, and things like that, so there was nothing in the house at all. So we didn’t know what was going on,” he said.

William added: “We had the privacy to mourn, to collect our thoughts, and to just have that space away from everybody.”

Britain’s prime minister at the time, Tony Blair, who was also interviewed by the makers of the programme, described the effect the death had on the British monarch.

“She was obviously very sad about Diana,” Mr Blair said. “She was concerned about the monarchy herself because the Queen has a very strong instinct about public opinion and how it plays.”

Diana died on August 31, 1997 from injuries sustained when a car she was travelling in, which was being pursued by paparazzi, crashed in the Pont de l’Alma underpass in Paris.