Looking flawless in a floor-length electric blue Roland Mouret gown - which is usually priced at over £2k, but is currently in the sale for £1,255 - Kate, 34, accessorised to perfection with a dazzling pair of Cartier diamond earrings and demure Gianvito Rossi heels.
Sports fan Kate has been a patron of the charity since 2013 and she met SportsAid ambassadors and young athletes who will be competing in the Rio 2016 Olympics at a pre-dinner reception.
Duchess Kate also mingled with some of the charity's key supporters, including former swimmer Sharon Davies, who looked super summery in her flowing coral-coloured dress.
Kate attended the event solo, perhaps leaving William on daddy duties to Prince George, two, and one-year-old Princess Charlotte, and as she carried out her royal duties.
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