Kate Middleton
Catherine, Duchess of Cambridge attends Royal Ascot 2017 at Ascot Racecourse on June 20, 2017 in Ascot, England.Chris Jackson/Getty Images

Kate Middleton, the Duchess of Cambridge, on Tuesday flashed her long legs in a see-through lace dress, and soon comparisons were drawn between her and the late Princess Diana, who showed off her pins in a sheer white skirt almost four decades earlier.

Diana was then a kindergarten assistant and this was one of the first photographs of hers since news of her romantic relationship with Prince Charles made headlines.

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The photograph showed Diana balancing a youngster on her hip, and dressed in a maroon sweater and while sheer skirt. The outline of her shapely legs was visible as the sun beamed behind her.

Arthur Edwards, who took the photo, told the Sun: "This was one of the first photos to make my name.

Diana was a class assistant at the Young England Kindergarten in Pimlico, London, in September 1980 and I started taking photos to capture the princess-to-be at work. But then the sun came out and made her skirt completely see-through. The shot made the front page of The Sun and people still ask me about it today."

Charles and Diana, Prince and Princess of Wales
Princess Diana and Prince Charles on a walk to the California Pavilion in Vancouver May 6, 1986.Reuters

Princess Diana has been in the news for the past few days, thanks to her biographer Andrew Morton's decision to release secret tapes where the princess opened up about dealing with her crumbling marriage to Prince Charles. She also revealed she attempted suicide multiple times since her royal wedding in 1981.

"She wanted these tapes to come out," Morton said during an appearance on Good Morning Britain, defending his decision to release the tapes now. "She was talking to me because she wanted it all published even though it was all undertaken in secrecy. She wasn't wasting her time.

"Princess Diana is now a major historical figure. People will still be writing about her in 300 years' time."

He added: "We all know the facts when it comes to her story. She herself went on TV and gave an interview to Martin Bashir about everything.

"To my knowledge, there are going to be 16 documentaries about her around the anniversary of her death. She is going to be celebrated this year, but at the same time, people cannot ignore her past. My book is Diana in her own words."