Since her debut at Celine two years ago, Phoebe Philo's legions of fans have gotten used to all things sleek and streamlined—be it the unadorned leather Classic box bag that launched so many imitators or the racing-stripe pants from Fall's car-inspired collection. But for Spring, Philo is thinking about shape. "It's just very sculptural, very three-dimensional," she said afterward. "We accentuated the bits that felt strong to accentuate, tried to create some new proportions."

You can count Philo among the growing number of designers who looked to fifties and sixties couture silhouettes for inspiration—as evidenced by the full, rounded sleeves of the army jackets, the Watteau backs of her blouses, the peplums circling the hips. You can also put her on the short list of those who made the era look modern and new. Chalk that up to the luxuriously spartan sensibility of the collection: no prints, no appliqués, few unnecessary extras save for the leather envelope bags and platform ankle-strap pumps that women will find very necessary indeed next spring (so much for the theory that platforms are over).

Basque was the designer's word for the peplums that were the show's focal point. Sometimes she used wide belts to create the effect; other times the flaring piece of fabric was only partially attached to a pair of trousers at the hips. That might draw the wrong kind of attention, but the slightly A-line leather tees and the collared cotton shirts with the graceful pleats down the back are a different story. And Philo didn't save her proportion play for the upper half. This season's pants were as billowy and fluid as last season's were linear.

It was an ambitious new message from a designer who's made a virtue of "reduced" fashion. Whether or not it has anything to do with the rumors she's been considered to replace Marc Jacobs at Louis Vuitton if and when he leaves for Dior, we'll have to wait and see.