Meghan's tuxedo mini dress was styled by her best friend, Jessica Mulroney

Meghan Markle caused quite the stir with a simple, chic tuxedo mini dress on Wednesday night - and now we have a clue as to who helped her style the outfit.

The Duchess of Sussex, 37, attended a performance of Hamilton in London with her beau Prince Harry, 33.

While the event was intended to raise awareness for the charity Sentebale, it was Meghan's sartorial choice that dominated the headlines.

The former Suits star wore a black button-down mini dress by Judith & Charlies, a Canadian tailoring label founded by husband and wife duo Charles Le Pierrès and Judith Richardson.

(They must have short memories, as Meghan frequently wore mini dresses, skirts and shorts during her red carpet heyday.)

According to royal reporter Omid Scobie, the stylist responsible for the much-discussed ensemble was none other than Jessica Mulroney, Meghan's best friend.

An Instagram post by Judith & Charlies also credited her for the Duchess' look, though this reference has since been removed.

Mulroney - a PR maven turned fashion advisor - met the future royal while she was based in Toronto during the filming of Suits.

The pair bonded over a mutual love of yoga and became firm friends, often holidaying together and featuring in one another's Instagram photos.

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The stylist and her husband, TV presenter Ben Mulroney, were also introduced to Prince Harry early in his relationship with Meghan, with the couples often dining together during his visits to Canada.

In fact, you might have spotted Mulroney hanging out with the royal couple during their first public outing at the Invictus Games last year.

Since Meghan's relationship with Harry became public knowledge, she's often turned to Mulroney for fashion guidance.

Several of the Duchess's most memorable looks - including the outfit she wore for the official announcement of her engagement to Prince Harry - have been styled by Mulroney.

The mother of three is also said to have been one of the few people privy to Meghan's Royal Wedding dress planning, reportedly flying to London for a top-secret designer fitting at Kensington Palace in January.

When her best friend said "I do" on May 19, Mulroney was seen arriving at Windsor Castle with the bridal party - which included her three children - moments before Meghan.

According to reports, her dark blue dress represented the bride's "something blue" - a gorgeous testament to their friendship.