Despite Thomas Markle Jr.’s plea to cancel the wedding, his half-sister will walk down the aisle and marry her prince next week.

However, the big royal events like this will require specific rules, especially concerning dress code. Even though the future bride broke many traditions, the correct appearance among the aristocracy is very important. British fashion critic Colin McDowell says:

According to McDowell, guests should be dressed in a correct way. With the always-changing fashion, it’s hard to say what kind of trends will prevail, but the fashion critic is certain women will wear hats and high heels, in agreement with tradition.

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Men, on the other hand, might opt for sneakers in lieu of dress shoes, but this bold move could be frowned upon in the uptight British circles. McDowell has one advice for all guests who are lucky to attend the royal wedding this year:

Traditionally, the U.K. weddings are far more formal than the American ones. Bare shoulders are big ‘no-no’ for ladies, and military uniform is welcomed for gents.

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When the Duke and Duchess of Cambridge wedded in 2011, Buckingham Palace distributed the 22-page list of dos and don’ts of the wedding attire.

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A morning formal wedding requires men to wear a cutaway coat, a vest, and pin-striped pants. A hat could be optional. Women are not allowed to wear floor-length dresses before the evening.

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For an afternoon wedding, the clues as to what to wear lie in the venue. A floral day dress might be a good choice for an outdoor venue, while a short cocktail dress is appropriate for the indoor one.

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A good tip to remember is to choose a simple dress but to spruce it up with a personal touch, like footwear, jewelry, or outerwear.

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It’s important for guests to know the biggest rule of the wedding day: You are not the star of the show.

Would you still like to be invited to the royal wedding?