Kate Middleton looked in stunning shape at a charity sports event in London today (Oct. 18) at Queen Elizabeth Olympic Park. (Photo by Ian Gavan/Getty Images)

Kate Middleton looked in stunning shape at a charity sports event at Queen Elizabeth Olympic Park in London today (Oct. 18). (Photo by Ian Gavan/Getty Images)

Kate Middleton, the future Queen of England, stunned onlookers today when her blouse flew up at a sports charity volleyball event and revealed her absolutely flat washboard stomach only three months after giving birth to her first child.

Prince George was born on July 12 and like all expectant mothers, Kate piled on pregnancy weight, although she was never what you would call heavy.

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But you would hardly know it now. She was photographed today (Oct. 18) at Queen Elizabeth Olympic Park in East London, her first solo public engagement since the birth.

She was participating in an event sponsored by SportsAid, a charity that supports young athletes.

As part of the activities, Kate, 31, joined an impromptu volleyball match. The 5-foot, nine-inch tall beauty, who is known for her athleticism and competitive streak, jumped right into the game.

Kate Middleton Shows Off Washboard Belly

She must have forgotten the paparazzi were watching her every move. As she jumped to return a ball, her Ralph Lauren breton-style top flew up to reveal her washboard belly.

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Kate was also wearing a pair of five-inch Stuart Weitzman for Russell & Bromley “corkswoon” wedges, according to London’s Daily Mail. Yet, she was extremely agile in them.

“She’s very tall and athleticism and we were all pretty impressed,” said Steve Williams, an Olympic rower, who joined her on the court. “She got a couple of slum dunks–I think technically they call them spikes–in there.

Kate, who is known for her slim physique, was photographed sunbathing topless at a chateau in France before she became pregnant, causing a huge sensation in Europe and Great Britain.

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She raised eyebrows because she appeared to gain very little weight during her gestation and seemed to lose it almost immediately. “Kate’s breastfeeding and the small weight she gained while pregnant has just melted off,” a source close to the Duchess of Cambridge claimed in August.

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Footnote: Prince George will make his next public appearance next week, Oct. 23, for his christening at The Chapel Royal in St James’s Palace