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Princess Kate opted for a white lace Alexander McQueen dress with a bespoke fascinator for the first day of Royal Ascot on Tuesday. The classic look channeled Audrey Hepburn's memorable style in My Fair Lady.
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William sported a stylish top hat on the first day of the five-day event.
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As crowds gathered in sweltering temperatures of up to 90 degrees, they were welcomed by the Queen, who arrived with husband Prince Philip, with a foreword in the official program.
In it, she celebrated "The tremendous racing and the gathering of 300,000 people and more than 400 horses from around the world makes this event unique.
"Last year, horses trained outside Great Britain won 14 of the 30 races and I am again delighted to welcome many overseas competitors.
"In 1711, Queen Anne declared Ascot to be 'ideal for horses to gallop at full stretch'. Ever since, the finest horses have raced here and that will certainly be the case again this week."
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Prince Charles and Camilla, Duchess of Cornwall make their way to the event.
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Princess Beatrice arrives in a pretty pink fascinator alongside sister Princess Eugenie.
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During the day, William and Kate and Charles and Camilla are scheduled to present a trophy.
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Kate chats with Princess Beatrice and Sophie, Countess of Wessex at the racecourse.
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The event also has a strict dress code. Ladies are kindly reminded that formal daywear is a requirement. Hats are also required. Dresses and skirts should be of modest length defined as falling just above the knee or longer. Strapless, off the shoulder, halter neck and spaghetti straps are not permitted.
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Gentlemen are kindly reminded that it is a requirement to wear either black or grey morning dress which must include: a waistcoat and tie (no cravats), a black or grey top hat and black shoes.
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Soon after the royals arrived in the Parade Ring, they led the racegoers in observing a minute of silence to honor the victims and families affected by the recent tragedy of the Grenfell Tower, and the terrorist attacks in Manchester and London.