Britain's Princess Charlotte of Cambridge stands and waves on the West Steps to wave off Britain's Princess Eugenie of York and Jack Brooksbank at St George's Chapel, Windsor Castle, in Windsor, on October 12, 2018 after their wedding ceremony. Getty Images/Andrew Matthews

Princess Charlotte has always worn dresses when she makes public appearances, and it seems there may be a reason why her parents Kate Middleton and Prince William prefer dressing her in frocks over pants.

Rachel Riley, a childrenswear designer who has dressed Prince George on several occasions, told The Telegraph that Middleton prefers the "traditional look" for her kids since they are a traditional family. She also said that Middleton may prefer buying dresses for Princess Charlotte rather than letting her try pants to avoid making the 3-year-old royal look "out of date."

“We have been doing very similar things for 18 years in that our collection is classic," Riley explained. "The reason why I design clothes that way is because if they wear very simple things, it’s about the child, and it’s timeless in that you can’t really date a specific photo or put them in something that seems out of date. I think they are going for clothing that is classic and timeless, rather than clothes that draw attention to them.”

But does royal protocol really prohibit Princess Charlotte from wearing pants in public? According to royal expert and Royal Musings blog founder Marlene Koenig, there isn't really a rule that bans pants from Princess Charlotte's wardrobe, just like there isn't one for mom Kate and aunt Meghan Markle, who have both worn pants in public multiple times.

"There are no rules about no pants," she explained. "If the Duchess is in a dress in public and Charlotte is with her, most likely Charlotte, at this age, will be in a dress – also in formal portraits, or on the balcony for the Trooping of the Colour."

Members of the Royal Family (L-R) Britain's Prince Charles, Prince of Wales, Britain's Catherine, Duchess of Cambridge (with Princess Charlotte, Savannah Phillips, Prince George) and Britain's Prince William, Duke of Cambridge, stand on the balcony of Buckingham Palace to watch a fly-past of aircraft by the Royal Air Force, in London on June 9, 2018. Getty Images/Daniel Leal-Olivas

Koenig previously pointed out that all females born to the royal family only wear dresses and never trousers when appearing in public.

"If you look at photos of young royal girls – from Princess Anne to Charlotte, you will notice that they tend to wear smocked dresses as little girls when they are in public with their parents," Koenig told Harpers Bazaar, adding that young female royals often get dressed up in "a clean, traditional look."

As for Queen Elizabeth II's opinion on young female royals wearing pants, it seems Her Majesty usually doesn't dictate what Princess Charlotte and her cousins wear. According to Koenig, Queen Elizabeth has "no say" in what Prince William and Middleton's daughter wears.

Koenig pointed out that it is likely Princess Charlotte, just like her older brother Prince George, wears casual clothes, including pants, when she's at home playing in the nursery or in the backyard.

And it seems the royal expert is right in her assessment as Princess Charlotte was once seen wearing shorts in 2016 when she was playing with her brother and their nanny. However, this wasn't an official public appearance.

Princess Charlotte
Princess Charlotte of Cambridge stands on the steps with her mother Catherine, Duchess of Cambridge after the wedding of Prince Harry and Ms. Meghan Markle at St George's Chapel at Windsor Castle on May 19, 2018 in Windsor, England. Getty Images/Jane Barlow
Princess Charlotte
Britain's Princess Charlotte of Cambridge leaves the christening of her brother, Britain's Prince Louis of Cambridge at the Chapel Royal, St James's Palace, London on July 9, 2018. Getty Images/Dominic Lipinski