You Won’t See Princess Kate in This! Pippa Middleton Wears a Seriously Sexy Blue Dress

Now that is one royally sexy gown.

Pippa Middleton put her marathon-toned figure on display when she wore a surprisingly sexy blue gown to the annual Boodles Boxing Ball in London on Saturday.

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The younger sister of Princess Kate accessorized the frock, which featured a halter neck and cut-out below her bust, with a blue bejeweled clutch and strappy heels.

Middleton, who turned 32 earlier this week, made the stop at the annual charity event — which is a favorite with the younger royal set — just a few days after she completed a grueling 47-mile swim-run competition in Sweden. The fruits of her intense training for the event could be seen on Saturday as her toned (and St. Barts-tanned) shoulders and arms were complimented by the blue dress.

While the Boodles Boxing Ball has been attended by the likes of Prince Harry, Prince William and Kate in the past, Middleton was the only royal (or rather, royal-adjacent person) in attendance this year. William’s friend Hugh van Cutsem was also spotted at the bash.

However, Middleton wasn’t alone at the event — she was spotted arriving with a group that included friend Tom Kingston.

WENN

For much more on Pippa’s ultra-athletic world, pick up this week’s issue of PEOPLE, on newsstands Friday

—Maria Mercedes Lara