Prince Charles and Princess Diana
Prince Charles and Princess Diana are pictured attending a centenary service for the Royal College Of Music on Feb. 28, 1982 at Westminster Abbey, London. Fox Photos/Hulton Archive/Getty Images

Princess Diana shared the “grave mistake” she regretted.

Princess Diana was involved in a number of controversies when she was still alive. Many felt that marrying Prince Charles was a wrong move. However, the princess had spoken up if there was something in her past that she wanted to change and the answer she gave didn’t involve the Prince of Wales.

In a conversation with Martin Bashir during her “Panorama” interview, the host asked the People’s Princess if she agreed that she had “very different outlooks and very different interests” compared to Prince Charles. The princess said “no” and pointed out that they shared a great deal of interest. For instance, they both liked people, country life and children. Both also worked in the cancer field and hospices. However, she admitted that she was “stupid.”

“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,” Princess Diana said.

“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.”

Prince William and Prince Harry’s mom claimed that the royal family didn’t give her 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,” the princess added.

In 1992, the Prince and Princess of Wales announced their split. After a year, Queen Elizabeth II invited Princess Diana to a state banquet in hopes that she and Prince Charles would reconcile, but the said move only infuriated the heir.

Ross Benson shared a different story about the state banquet that Princess Diana attended that year. According to the royal biographer in his book “Charles: The Untold Story,” Princess Diana suddenly phoned and informed the Queen that she would be attending the event.

The People’s Princess was banned from every royal occasion unless Her Majesty allowed her presence. However, the Queen couldn’t bring herself to say that Princess Diana was not welcomed to the event since she was frightened of her daughter-in-law’s influence.