The footage, which was recorded on a camcorder at Kensington Palace in 1992/93 by Diana's speech coach, former Coronation Street actor Peter Settelen, contains deeply personal revelations about her marriage to Prince Charles.
When Diana confronted her husband about his infidelity, she says he replied: "I refuse to be the only Prince of Wales who never had a mistress."
She also claims Prince Philip told Charles that if the marriage did not work out, he could go back to Camilla "after five years".