The Piranha 3D star attended the Evening Standard Theatre Awards in an eye-catching maroon-coloured dress that was slashed to the hips.

However, a gust of wind left the British beauty struggling to preserve her modesty when the frock fell wide open, exposing her knickers to the watching photographers.

Kelly, who turns 36 on Monday (23Nov15), quickly adjusted the dress and attempted to laugh off the incident as she headed into the ceremony at London's Old Vic theatre.

She later hinted about the incident in a comment on Twitter.com by posting a photograph of herself looking demure on the red carpet, alongside the caption, "The Calm before the Storm."