Princess Diana's Split-Second Decision That Led to Her Signature Haircut

Getty Princess Diana in Versace in 1996

Princess Diana's signature hairstyle came from an impromptu cut.

Sam McKnight, who became the royal's personal hairstylist from 1990 until her tragic death in 1997, opened up about the memorable first time he met Princess Diana in a new video for British Vogue and YouTube U.K.

"The first time I met the Princess of Wales was on a shoot," he said. "This leggy blonde comes bouncing up the stairs, smiled and made us all melt, and it was Princess Diana."

McKnight said they had a "really lovely day" doing portraits for British Vogue, in which he played with her hair.

"I made it look short under the tiara — I faked it a bit," he said.

RELATED: Prince Charles Exploited Diana's Love of Fashion to Make Her Seem 'Frivolous,' Book Claims

When the photoshoot wrapped, Princess Diana asked McKnight how he would do her hair if she let him do whatever he wanted.

"I said, 'I would cut it all off and just start again,' " he recalled. "It was the beginning of the '90s and it was at the time that I was doing lots of shows and covers and a lot of the girls had short hair, and we were moving from the big frou-frou '80s into the sharp, more androgynous, business chic of the '90s."

Can't get enough of PEOPLE's Royals coverage? Sign up for our free Royals newsletter to get the latest updates on Kate Middleton, Meghan Markle and more!

In a surprising move, she said, " 'Well, why don't you just cut it off now?' So I cut it off then and we never looked back," McKnight shared.

McKnight also remembered another royal highlight of his career: when Princess Diana met his mother during a visit to a factory near the Scottish village where his mom lived.

"My mum and her friends were standing outside and [Diana] had never met my mum before. So, I think the story goes, one of my mum's friends shouted out, 'This is Sam's mum,' and for some reason the Princess knew exactly who she was talking about and went over and spoke to her and that made my mum's day," he said. "I think for me that was probably the most pride I've ever felt in my job."

Get the premiere issue of PEOPLE Royals for glamorous new photos and inside stories royals fans haven't seen or read elsewhere! Subscribe at peopleroyals.com/launch

Last year, McKnight worked with TV's most famous Princess Diana actress for another Vogue cover: The Crown's Emma Corrin.

"From one Princess Diana to another," the stylist said. "I remember that day. That was my first job after the first lockdown in summer [2020] and I remember when the job came in I wasn't quite sure that I was the right person to do this... And actually it was a pleasure and Emma was a pleasure, and I was quite taken by how alike Emma was to Princess Diana in her looks. And she was such a lovely girl that any doubts and fears were laid, and I think it's a great cover."