Princess Eugenie's rarely-seen corset wedding guest dress for Prince William's nuptials

A royal wedding may come with expected fashion rules and regulations for the ceremony, but the dress code can be a little more rebellious for other celebrations.

Take the Prince and Princess of Wales' pre-wedding party, for example, which saw the royals gather in their droves dressed to the nines. One of those guests was Prince William's cousin Princess Eugenie , who looked sensational in a black corset evening gown that accentuated her waist. Other features included a cowl neck, an embellished flower on the strap and a flowing skirt, which partially concealed her patent stiletto heels.

© Pascal Le Segretain

Embracing her Hollywood glamour look, Eugenie carried a sparkly clutch bag, accessorised with a giant ring and styled her brunette hair into bouncy curls.

She was joined by the Duchess of Edinburgh, the late Queen Elizabeth and Princess Beatrice at the pre-wedding dinner at the Mandarin Oriental Hyde Park on 28 April 2011, hosted by the Queen’s cousin Lady Elizabeth Shakerley.

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Her elder sister wore an eye-catching tulle mermaid gown with bold silver sequin embellishments and a one-shouldered neckline – a departure from the demure necklines and covered shoulders the royals often sport.

Meanwhile, her cousin Zara Tindall chose a similar black floor-length gown to Eugenie, featuring one strap and a figure-hugging silhouette, with her blond hair in a voluminous beehive style.

© Danny Martindale

William and Kate's wedding preparations

Two important guests who were notably absent were William and Kate, who spent the night away from the festivities in preparation for their ceremony on 29 April.

Kate spent the night at the five-star Goring Hotel in the Royal Apartment, which boasted a four-poster bed, a grand piano and a walk-in shower following a £150,000 makeover.

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Meanwhile, Prince Harry claimed in his book Spare that the groom turned to rum to calm his nerves. His brother was supposedly "tipsy" as they greeted members of the public on the Mall who had lined up to get a front row view of the wedding.

"Willy, rum-warmed, shouted: 'We should go and see them!' He texted his security team to say he wanted to do so.

"The security team answered: 'Strongly advise against.'

"'No, he shot back. It’s the right thing to do. I want to go out there. I need to see them!' He asked me to come. He begged. I could see in his eyes that the rum was really hitting hard. He needed a wingman," Harry penned.

Wedding outfits

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The couple tied the knot at Westminster Abbey before inviting 650 guests to a lunchtime reception at Buckingham Palace hosted by the late Queen Elizabeth II.

The bride wore two Alexander McQueen wedding dresses for the occasion – the first was a corseted dress with a full skirt and sheer lace sleeves, while the second was a strapless satin number with an embellished belt.

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Just 300 people including Princesses Beatrice and Eugenie, Lady Kitty Spencer and William van Cutsem attended the evening reception at the Palace, where they changed into evening attire.

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In Eugenie's case, she swapped her vibrant blue Vivienne Westwood dress and feathered Philip Treacy fascinator – which proved a controversial choice among fans – for a red flowing gown with off-the-shoulder straps and nude stilettos.

LOOK: Princess Kate's pre-wedding dress is still one of her best outfits