Kate Middleton 'Significantly Changed Her Appearance' in Order to Marry Prince William

Kate Middleton and Prince William's love story began during their university years at St Andrews, and throughout their decade-long courtship, Kate's style slowly evolved as she got closer to becoming a Windsor.

An outlet reported the Princess of Wales “significantly changed her appearance to become more appropriate” for William's royal status.

"We hadn't expected Kate and her family to turn up, and myself and a number of photographers and journalists were all standing on a press stand together," expert Rebecca English said in William & Kate: Too Good To Be True when discussing Kate showing up to William's 2006 passing out parade.

"Suddenly, out of the corner of her eye, we saw Kate and her mother and father being ushered down to the front of the seating," English stated. "I remember turning to the person next to me and saying, 'That's it, it's a done deal. This woman is going to be our future queen.'"

Shortly after Kate was spotted at the official gathering, the public began to speculate that the then-boyfriend and girlfriend would eventually wed. (The Wales tied the knot in 2011.)

"Suddenly, the engagement whispers were starting," she continued. "There was intense pressure on William and Kate, and, short of printing the tea towels, everyone had these two walking down the aisle imminently."

When Kate and William got married, the Princess of Wales was 29, and she quickly matured her outfits to transition into becoming the Duchess of Cambridge.

“Kate’s fashion sense changed rapidly as she adjusted to life in the royal spotlight, going from girl next door to elegant future queen," English said.

"The low-slung jeans, denim skirts, and spaghetti straps of her early 20s were swapped out for smart blazers, quality suits, and refined gowns, with a more polished, Palace-ready look emerging," she explained.

Author Tom Quinn shared a similar sentiment in the documentary.

"Her clothing almost began to reflect what people saw in her character — a kind of restraint, kind of modesty almost,” Quinn noted.

“I think that did come about because William and Kate were coming towards the point where they would announce their engagement. It was Kate starting to behave in ways which would be seen more appropriate for a future queen," he added.

OK! previously reported fashion expert Miranda Holder analyzed how Kate's approach to trends changed in her fourth decade of life.

“Kate is saying, ‘Don’t focus so much on my clothes. I am here to do a role,'" Holder said in an interview. "I want to be taken seriously. I am treating this as a proper duty."

Since becoming the Princess of Wales, Kate has been seen in more pantsuits and ensembles associated with women in the C-suite.

"I’m pledging my allegiance to these charities and causes. … I’m your future queen, and I’m doing the best I can,'" she said. "It’s sending out a message of business rather than fashion. … [She’s] trying to take away from the world’s — including my [own] — fixation on [her] fashion."

Holder later applauded Kate's ability to gracefully juggle royal duties, motherhood and being an influential figure.

“She’s definitely a wonderful mother, a lovely wife, and we all adore her, but she’s very, very committed to her role and she puts everything into whatever she’s doing, and that’s reflected throughout her life,” Holder explained. “Her wardrobe needs to reflect that, and she’s worked really hard over the years to refine her look."

The Mirror reported on Kate's style.