Prince William and Prince Harry were just 15 and 12 when their mother, Princess Diana, was suddenly killed in a car crash in Paris. The tragic event which shocked the world happened 20 years ago this August, causing many to reflect on the heartbreaking loss of the much-loved ‘People’s Princess’ and the events that followed her untimely death.

Prince William and Prince Harry have already spoken about their mother in a touching documentary created as a tribute to her called Diana, Our Mother: Her Life and Legacy.

Now, her sons are speaking out once again for a BBC documentary called Diana, 7 Days focusing on the difficult days following her death.

Speaking in the BBC documentary, Prince William has opened up for the first time about the day the world watched he and his brother walk behind their mother’s coffin.

Speaking of the procession, engrained in many people’s minds for it’s heartbreaking poignancy, William says, “It was one of the hardest things I’ve ever done, that walk. It felt she was almost walking along beside us to get us through it.”

His brother Harry remembered being comforted by members of the public whose ‘hands were wet because of the tears they had just wiped away’.

A couple of months ago, Prince Harry also opened up about that devastating day, and how he felt walking with his brother, father, uncle and grandfather behind his mother’s coffin.

In an interview with US magazine Newsweek, he stated, “My mother had just died, and I had to walk a long way behind her coffin, surrounded by thousands of people watching me while millions more did on television.

“I don’t think any child should be asked to do that, under any circumstances. I don’t think it would happen today.”

One of the Queen’s most trusted aides has also come forward to reveal that the decision for Prince William and Prince Harry to walk in the procession behind their mother’s coffin was not made until the very last moment.

Remembering the incredibly difficult time, Sir Malcom Ross – who was also responsible for planning the events surrounding Diana’s funeral – revealed that the subject of the Prince’s involvement wasn’t raised until a ‘family supper’ the night before the heartbreaking day.

Speaking in a new ITV documentary called ‘The Day Britain Cried’, Ross reveals, “The involvement of the princes on the day, we didn’t address until the last possible moment. “

“I understand it was at a family supper on the Friday night at Buckingham Palace that the decision was made and Prince Philip, after some discussion, said to the boys, “I’ll walk, if you walk”.”

Diana, 7 Days will air on the BBC on August 27