Without seemingly breaking into sweat despite the soaring temperatures, the brunette completed a 5km race in 25 minutes and 30 seconds.
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The 26-year-old is no stranger to athletics, having won a sports scholarship to Marlborough College.
Clad in a pink and grey tank top with matching shorts, Pippa kept her £270 pair of Bulgari sunglasses perched on her head as she breezed through the race, which was held at Blenheim Palace in Oxfordshire.
She was joined by two male friends and opted to do the running part of the competition while the boys completed tough swimming and cycling sections.