Dressed in a buttery beige Valentino coat adorned with intricate coiled collar detailing and a pretty bow belt, the Princess' tailoring was unique and understated - until she added that Philip Treacy hat.
WATCH: Princess Beatrice's most memorable fashion moments
Her blush pink fascinator, reminiscent of a rippling starched ribbon made Princess Beatrice the subject of Internet mockery at the time. Our thoughts? The world just wasn't ready for millinery that magnificent.
Princess Beatrice wore a fascinator designed by Philip Treacy
Yet amid her so-called sartorial faux pas, the daughter of Prince Andrew and Sarah Ferguson had a spellbinding fashion moment the night before William and Kate's wedding that went under the radar - and we're here to revive it.
Princess Beatrice attends the pre-wedding dinner at Mandarin Oriental Hyde Park on 28 April 2011 in London, England.
24 hours before Prince William and his bride-to-be, Catherine Middleton, tied the knot in a fairytale wedding ceremony watched by 2 billion viewers worldwide, the late Queen Elizabeth II hosted their closest friends and family for a pre-wedding dinner at the Mandarin Oriental.
The glittering affair was attended by the British royal family and royalty from around the world, and came with a dazzling dress code.
Princess Beatrice's dress was stitched with silver sequins
Looking every inch a Princess for the occasion, Beatrice, then 22, slipped into a blush pink mermaid-style dress. Boasting layers of ruched tulle embellished with glittering silver sequins, the royal's asymmetrical gown remains one of the most striking dresses she has ever worn.
Princess Beatrice's auburn hair was styled in sleek, glossy curls, as she elevated her defined facial features with a silver smokey eye and blush pink lip gloss.
Queen Elizabeth II and Prince Philip, Duke of Edinburgh pictured leaving tge pre-wedding dinner held at the Mandarin Oriental Hyde Park
Interestingly, the Prince and Princess of Wales weren't present at their own pre-wedding celebrations, instead choosing to spend the evening quietly as they geared up for the most important day of their lives.
Almost 14 years on from the unforgettable day, few can forget the moment Kate stepped out of a 1978 Rolls-Royce Phantom VI with her father, Michael Middleton, and unveiled her breathtaking Alexander McQueen wedding dress for the first time.
The Princess of Wales' dress was designed by British designer Alexander McQueen
Thought to have cost Carole and Michael Middleton £250,000, the bride's gown featured handmade lace created by the Royal School of Needlework and an ivory satin Victorian-inspired corset bodice which was "narrowed at the waist and padded at the hips", according to the Palace.
It was finished with 58 organza-covered buttons and a skirt that "echoes an opening flower."
ROYAL FAN? JOIN THE CLUB
Welcome to The HELLO! Royal Club, where thousands of royal fans like you get to delve deeper into the wonderful world of royalty every day. Want to join them? Just click the button below for a list of club benefits and joining information.
Sign up to Royal Style and discover the latest royal fashion moments
By entering your details, you are agreeing to HELLO! Magazine User Data Protection Policy. You can unsubscribe at any time. For more information, please click here.