The pair married on July 29, 981 at St Paul's Cathedral in a ceremony that was watched by almost 750 million people worldwide.
The night before the 1981 Royal Wedding of Prince Charles and Princess Diana, the royal couple sat down together with interviewers Andrew Gardner and Ms Rippon to answer questions about their relationship and how they viewed their future as husband and wife.
During the interview, which aired on Thames Television, Diana was also questioned on adjusting to royal life and if Prince Charles had been helping her to do so, to which she responded that Prince Charles had been, 'Marvellous, a tower of strength'.
Charles, in response to her remark, jokingly said, 'Oh gracious. Encouraging.'
The interviewers are seen laughing along with Diana and Charles before Diana cheekily replied, 'I have to say that because you're sitting there', which prompted Charles to twiddle his fingers and roll his eyes.