The royals follow a strict protocol in their daily lives, and this includes fashion choices. There are many unofficial style conducts that working royals are meant to follow, and most follow them religiously.
But, it's fair to say that some loopholes can be found and the late Princess Diana often ignored quite a few of these rules, and coincidently, so did the Duchess of Sussex when she was a working royal.
However, the Princess of Wales has stayed innately faithful to these rules and hasn't once deterred from them.
Tights
Tights, or pantyhose as the USA calls them, are meant to be worn for public engagements if one is wearing an item where the legs are on show.
Diana often went bare-legged, and tights are something Meghan often skipped, too.
Prince William's wife Kate, however, seems much more comfortable in stockings and regularly wears them.
Black dresses
A big royal rule is to only wear black when in mourning. Despite the shade being the most fashionable colour out there, it really should only be reserved for funerals, according to royal protocol.
Prince William and Harry's mother often defied this. Dame Zandra Rhodes recently confirmed this in an interview with Saga Magazine, revealing that Diana loved black dresses, especially as daywear.
The fashion designer revealed: "She was very shy. She would come into my shop in Mayfair and go through the rails. Sometimes she picked something in black, which the royals weren't allowed to wear except at funerals, so we would make it in her size in a different colour."
Famously, Diana wore a show-stopping black gown by David and Elizabeth Emanuel to a fundraising concert. Many years later, Diana was interviewed for her biography, and reportedly revealed that when Charles saw her in the dress, he remarked: "Only people in mourning wear black!"
Meghan took a leaf out of her late mother-in-law during her time as a working royal, and largely stuck to an all-black wardrobe ever since her fairytale royal wedding to Prince Harry in 2018.
Meanwhile, Kate never wears black to royal engagements other than during a period of mourning.