Princes William and Harry have given their ‘final word’ on Princess Diana

Prince William and Prince Harry have given their "final word" on their mother Princess Diana as her 20th death anniversary approaches. The royal brothers star in the BBC's new documentary Diana, 7 Days, which is set to air on Sunday night. Filmmaker Henry Singer says this is the first and perhaps last time William and Harry will speak publicly – and in depth – about their mother.

"I think the Princes hope they have answered these questions once and for all," Henry told Radio Times. "And they don't need to be asked them anymore, and that people can refer back to this film and our words within it if they have questions. That this is their first, and final word on it." He added: "My film may not have the headlines that other films have had, but I would like to think I will do something that lasts the test of time, and that, for me, is much more important than breaking news."

Earl Spencer, Princes William and Harry, and Prince Charles at Diana's funeral

Henry, who made the Twin Towers documentary The Falling Man for the fifth anniversary of 9/11, said he was allowed to ask the Princes anything for the BBC's new 90-minute programme, but they could choose not to answer. "They talk about coming down to London, what it was like to go outside, and how people were so anxious to see them, and how people were crying, and yet they didn't cry," he said.

In the documentary, which charts the seven days following Diana's shock death, William speaks of viewing the funeral procession through the "safety blanket" of a bowed head and his long fringe. Harry, who was 12 at the time, also talks about deliberately trying to suppress any tears while the huge crowds around him were weeping openly.

"I remember people's hands were wet because of the tears that they had just wiped away," said Harry, speaking in the 30-second trailer. Of walking behind his mum's coffin, William added: "It was one of the hardest things I've ever done, that walk. I felt like she was almost walking along beside us, to get us through it."

Earl Spencer, Princes William and Harry and Prince Charles at Diana's funeral