Dimbleby quizzed the prince: “Did you try to be faithful and honourable to your wife when you took the vow of marriage?”
Junor discussed what happened next.
“‘Yes, said the prince, and after a brief and rather anguished pause said, ‘until it became irretrievably broken down, us both having tried,” said Junor.
She continued: “The Duke of Edinburgh was incensed, the rest of the family flabbergasted, the Queen’s advisers and courtiers stunned, the prince’s friends appalled.
“The blame fell squarely on (private secretary) Richard Aylard for having allowed Charles to make what many regarded as the worst mistake of his life.
“The Queen and the Duke were appalled by 'The Prince of Wales', the book Jonathan Dimbleby wrote about the prince in 1995 following the disastrous film, and hurt by the picture he drew of his childhood.
WATCH: Scared Diana's 'tense' interview with Charles