Why Princess Kate Always Slants Her Legs When She Sits (and Diana Did Too – and So Should You!)

As Princess Kate sat on the famous " Diana bench" alongsidePrince William at the Taj Mahal on Saturday, she sat in a distinctive, and very elegant way – her knees and ankles were clasped firmly together and her legs were slanted to the side, creating a zig-zag effect as she posed for photographs.

It's a pose she's struck many times before. In fact, eagle-eyed royal fans may notice that she almost always sits with her legs leaning to one side whenever she's seated at a public event. And, as it turns out, the signature pose likely has to do with etiquette, and it has already earned its own name – the "Duchess slant."

The unofficial term, first coined by Beaumont Etiquette, is named after the Duchess of Cambridge and her now go-to pose.

"Typically 'the Duchess Slant' is used when a lady has to sit for an extended amount of time while keeping poise and posture," Myka Meier, royal etiquette expert and founder and director of Beaumont Etiquette, tells PEOPLE. "It is the perfect pose for when a camera is shooting directly in front of you because by slightly slanting the knees to create a zig-zag effect when wearing a dress or skirt, your legs are angled so that the camera only shoots the sides of your legs and protects your modesty."

Meier also adds that the slant helps make your legs look longer when sitting.

"'The Duchess Slant' is one of the most elegant and flattering ways to sit, because it has a lengthening effect on the legs," she says. "The key with the technique is to square your shoulders straight ahead while maintaining perfect posture. Keeping knees and ankles together at all times, position your legs so that you create a slant, angling your knees to the side. Hands should be folded one over the other and placed in your lap."

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Of course, Kate isn't the first woman – royal or otherwise – to lean her legs to the side while sitting. Princess Diana would sometimes lean her long legs while posing for seated photos, and even struck that same slant in 1992 while posing on that now famous bench outside the Taj Mahal.

As Meier, notes, one of the "biggest etiquette mistakes a lady can make" is to cross her legs at the knee. Instead, women should sit with their knees and ankles together and should only cross their legs at the ankle if needed. "It's sophisticated, protects vulnerabilities and looks fabulous in photos," Meier says.

Turns out, when you're a royal, even the way you sit is carefully orchestrated around etiquette.