Recordings of Princess Diana speaking candidly about her sex life with Prince Charles and her sorrow at the spectacular collapse of her marriage will be broadcast on British television on Sunday.
Diana, the first wife of the heir to the British throne, died aged 36 in Paris on August 31, 1997, after the limousine carrying her and lover Dodi al-Fayed crashed in a tunnel as it tried to escape paparazzi who were chasing them on motorbikes.
Diana was just 19 when she was betrothed to Charles in 1981, but the marriage broke down. Diana blamed Camilla Parker Bowles, Charles's lover who later became his wife, for the collapse of the marriage.
In a documentary planned to coincide with the 20th anniversary of Diana's death, broadcaster Channel 4 will show footage of her speaking about her marriage during privately recorded sessions with an adviser on public speaking.
The footage includes Diana speaking about her sex life with Charles.
"It was just so odd. I don’t know there was no requirement for it from his case," Diana says. "Sort of once every three weeks."
"And then I followed a pattern, he used to see his lady once every three weeks before we got married," she said.
Diana also relates how she approached Queen Elizabeth to discuss the failing marriage.
"She said, ‘I don’t know what you should do, Charles is hopeless’. And that was it," Diana said.
She also said Charles's father, Prince Philip, had given him permission to have an affair if the marriage did not work.