Princess Diana's iconic 'revenge dress' celebrates milestone

Princess Diana was always known for her style.

But there was one dress that said so much more than 'style icon', it coined it's own term - the 'revenge dress'.

On June 29, 1994, the Princess of Wales stepped out at the Vanity Fair party at the Serpentine Gallery in London in an off-the-shoulder black knee-length dress by Christina Stambolian.

The dress was a last minute pick for the Royal after her original dress choice was leaked.

But 25 years on, the velvet number accessorised with a pearl and sapphire choker, is as iconic as ever.

The dress was a big moment for Diana because the event was on the same day Prince Charles admitted to his affair with Camilla Parker-Bowles, the relationship which ultimately led to the couple's divorce.

LISTEN: A closer look at Princess Diana's impact on the Royal Family in The Windsors (Post continues.)

Originally, Diana was planning to wear a Valentino number, says royal biographer Andrew Morton.

"She got highly irritated when Valentino sent out a press release beforehand saying she was going to wear their dress, because she thought it was presumptuous," he told Daily Mail.

Morton says a close friend of Diana's, James Colthurst, advised her to ditch the designer gown and opt for a saucier look.

"She said to him she was so annoyed with Valentino, and he said, 'Well, I don’t know, look, wear something else, something sexy.'

“She said, 'I probably will'," Morton says.

Whatever the reason for the choice, Princess Diana decision resulted in both a personal and professional win, grabbing the front pages and the headlines from her husband.