Her Majesty was joined by Prince Andrew as she waved to royal fans during the traditional carriage procession along the Berkshire racecourse.
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The royal was positively beaming in her lime green outfit, having already stepped out in bright pink and different shades of blue this week.
The 93-year-old monarch is known for her love of horses and is a breeder of thoroughbreds.
A host of senior members of the royal family attended the prestigious evening including Prince Charles, Camilla, Duchess of Cornwall, Prince William, Kate Middleton, Princess Eugenie and Princess Beatrice.