Kate Middleton just broke a royal protocol.

On Tuesday, the Duchess of Cambridge accidentally flashed her “killer legs” during a visit to Bletchley Park to view a special D-Day exhibition. Middleton donned a navy blue polka dot dress by Alessandra Rich with a thigh-high slit for the outing.

A gust of wind caught the duchess’ dress, exposing her thighs that Prince Harry once described as “killer legs.” Following the exposure of Middleton’s thighs, Claire Anderson of Express said that the duchess violated a royal protocol. Anderson was referring to the rule of royal ladies wearing tights.

When Middleton’s legs were exposed, it appeared that she was not wearing one even if this is “the only steadfast rule in term of what the Queen requires.

“You never see a royal without their nude stockings,” royal expert Victoria Arbiter said.

When Prince Harry and Meghan Markle announced their engagement, the Duchess of Sussex was slammed for the same reason. She didn’t wear a pantyhose during the photocall.

According to Fashion Magazine, this is a tradition that Queen Elizabeth II, Middleton and other ruling ladies that came before Markle uphold. However, it seems that the Duchess of Cambridge failed to exercise it in her recent engagement.

According to celebrity journalist Ashley Pearson, Middleton has a whole other set of rules and restrictions because she is going to be a queen one day. Markle and Middleton are not on the same page.

In fact, Middleton has to wear her skirts at a certain length. The Queen also reportedly sends her notes regularly if Her Majesty doesn’t like a certain hem or outfit on Middleton including the color of her tights.

On Monday, Middleton will be having a big moment at the Chelsea Flower Show. The duchess designed a garden for the event and it will be showcased on that day. Middleton co-designed the garden with the Royal Horticultural Society and award-winning landscape architects Andrée Davies and Adam White.

Middleton’s garden is designed to suit all ages. It has child-friendly touches including a tree house, a swing seat, a campfire and a rustic den similar to what Prince George, Princess Charlotte and Prince Louis use in the grounds of Anmer Hall.

Queen Elizabeth II will be there to support Middleton. Her Majesty will be accompanied by other members of the royal family.

Kate Middleton Kate Middleton reacts as she arrives to launch a new national support line at the charity, Family Action on January 22, 2019 in Lewisham, England.  Photo: Getty Images/Adrian Dennis