The party planner-turned-columnist was writing an article for The Spectator, and described her sporting achievements at Marlborough College, the school she attended alongside Kate.
Pippa, the proud captain of the hockey team, reminisced on her "undeniably fanciable coach" and her attempts to impress the boys watching from the sideline.
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"When I close my eyes and think about school sports, I envisage myself on the hockey pitch, stick in hand, a luminous gumshield locked on to my chops and a bandana across my forehead," wrote Pippa at the opening of her article.
"Boys are watching," she went on. "I can also hear the booming voice of Mr Markham, our fierce but undeniably fanciable coach, urging us all on.
"My focus is on winning and making sure that my hair — fashioned into a slick Sporty Spice 'up do' — is just right. Did I mention the boys watching?"
The sporty schoolgirl described how she and Kate had always been strong athletes, never copping out of cross-country runs compared to her fellow classmates.
"Unlike many of my friends who 'suddenly got the flu', we Middleton girls were always at the starting line — albeit reluctantly — fuelled by Lucozade tablets and bananas," added Pippa.
The younger sister of the Duchess is a known tennis fan, and earlier this year was spotted cheering on her favourites from Wimbledon's courtside. Pippa, 29, was accompanied by her boyfriend Nico Jackson, who she was first linked to at the beginning of the year.
It has been speculated that the lovebirds will announce their engagement within months, according to close friends of the couple.
"An engagement is definitely on the cards," said a source. It is thought the columnist has been delaying the news out of respect for Kate, who gave birth to Prince George in July.