In November 1995, Princess Diana shocked the world and rocked the House of Windsor to it's core with her BBC Panorama national broadcast.
The now-infamous interview, which laid bare the state of the Princess' union with Prince Charles, also revealed Di's biggest regret from her time inside the royal family.
While many might assume this related to her iconic declaration "there were three of us in this marriage"- referring to herself, the Prince of Wales and Camilla Parker-Bowles - the People's Princess wished she could change an entirely different part of her past.
Before we get into it, watch this video to see Diana's heartbreaking account of Charles and Camilla's affair:
In conversation with Martin Bashir, Diana was asked if she agreed that she had "very different outlooks and very different interests" to her estranged husband, the Queen's son.
The Princess replied: "No, I think we had a great deal of interest - we both liked people, both liked country life, both loved children, work in the cancer field, work in hospices.
"But I was portrayed in the media at that time...as someone - because I hadn't passed any O-levels or taken any A-levels - I was stupid.
"I made the grave mistake once of saying to a child I was as thick as a plank, in order to ease the child's nervousness, which it did - but that headline went all round the world, and I rather regret saying it."
Diana, Princess of Wales in November 1995, the same month her Panorama interview was broadcast
Diana sensationally claimed the royal family had not allowed her to have any hobbies or interests, and lamented how she was never "given any credit for growth".
"Anything good I did nobody ever said a thing, never said 'well done'. But if I tripped up, which invariably I did...a ton of bricks came down on me," she said.
The Wales' divorce was finalised on August 28, 1996.
Tragically, barely one year later, Diana was killed in a car crash at the Pont de l'Alma tunnel in Paris on August 31, 1997.
Prince Charles married Camilla, now Duchess of Cornwall, in a civil ceremony at Windsor Guildhall on April 9, 2005.
Alice MurphyAlice Murphy is a freelance journalist and self-professed news addict. Originally from Ireland, Alice is on a mission to visit every country in the world (telling stories along the way). She is most commonly found eating sushi, drinking strong coffee and reading horoscopes.