This is the one colour that Meghan Markle and Kate Middleton refuse to wear

While you'd expect the future Queen and the newly appointed Duchess of Sussex to be more than the sum of their sartorial parts, it often doesn't feel that way.

Meghan Markle's wedding dress - Givenchy, by way of Clare Waight Keller - was undoubtedly dissected by every last one of the 29 million people who tuned into the nuptials. And despite being a member of the royal family for seven years now, Kate Middleton can't step outside without the tabloids commenting on the length of her skirt, or why she opted to wear wedges - a choice of footwear that Her Royal Highness reportedly dislikes.

It does make sense, however - being a member of Kensington Palace means that you need to dress in a certain manner, what with all of the rules and regulations - but the fashion "no-no" that we're discussing today has nothing to do with palace rules, and more to do with being a celebrity.

It's known that Meghan enjoys wearing more muted, neutral tones, while the Duchess of Cambridge's closet is full of colour-blocking looks, that range from red and pink to blue and green.

But you may have noticed that there's one colour that neither of the Duchesses have ever worn - and probably never will. Harpers Bazaar reports that Kate and Meghan have never been spotted out and about in orange. And while it's not part of royal protocol to avoid the shade, it's a colour that doesn't photograph well, and so tends to be avoided by celebrities in general - according to The Express.

People magazine recently reported that the erstwhile actress "has found certain rules in the royal household difficult to understand, like the fact that the Queen prefers women in dresses or skirts rather than trouser suits, and is often asking Harry why things have to be done in a certain way."

"I think she finds it a little frustrating at times, but this is her new life, and she has to deal with it," the source continued.

Meghan's style has certainly evolved since joining the royal family. In all of her official royal engagements to date, the 37-year-old has opted to wear more traditional designs with a muted colour palette. This is especially evident when she's with the Queen. While Her Majesty is rarely seen out of her signature brights, Meghan chose to don a blush pink Carolina Herrera dress at Trooping the Colour. And then, at their solo outing to Chester, the Queen wore a lime green ensemble, whereas Megan wore a nude Givenchy dress.

This is, of course, a far cry from the way that Meghan dressed herself when she was an actress, and before she got engaged to Prince Harry.

This is all to ensure that the monarch takes centre stage at public outings - a fact that was confirmed by fashion commentator, Lucas Armitage. Speaking to the Daily Mail, she stated "I feel this is a clever styling tactic as it will always work with the Queen's look; she is known and applauded for her use of bright fun colours."

Fair play.