Setting the tone for the day, the 83-year-old monarch - who arrived in a horse-drawn carriage with Prince Philip - chose to wear a golden yellow and white silk Stuart Parvin dress, teamed with matching accessories and an elegant hat, to the start of the five-day long sporting event.
Following suit was her daughter Princess Anne in a summery frock teamed with a fitted citrus-hued jacket and matching headwear. Twenty-year-old Princess Beatrice was not only on trend with her choice of colour, but also showed she's a savvy high street shopper. The young royal teamed her emerald green dress with a cropped jacket from Kate Moss' Topshop range and heels from Office.
It wasn’t just members of the royal family upping the style stakes. Katherine Jenkins stood out from the crowd in a hot pink dress and hat complete with oversized decorative floral blooms. Britain's Got Talent judge Amanda Holden, seen cheering on the horses with husband Chris Hughes and fellow talent show judge Simon Cowell, was no less resplendent in a red Fendi number and a red and black ostrich feather headpiece.
The first day of the racing event, which is a highlight of the summer social scene, was also attended by Prince Charles and Camilla - who wore a Vivienne Westwood dress and coat in neutral tones. The Duchess presented the trophy to the winner of the first race, the first time she'd handed out a prize at Royal Ascot.
The Queen, a keen race enthusiast, has six horses in this year's event, the largest number of runners she's entered for some time. Her first mount, Instalment, will run on Wednesday.