Ann Demeulemeester, to the relief of her many followers, is by nature a trend refusenik. She carved out her aesthetic—that slouchy, layered, definitively Belgian thing—long ago, but still, there's always something subtly permeable about her parameters. This Spring, there's a floppy flowiness to her masculine-feminine design that picks up a sense of the thirties, and plays on bold stripes, fringing, feathers, and languid washed satin.

All this, of course, happens within the established template of Demeulemeester's tailoring—monochromatic soft linen coat jackets, elongated vests, and pants. This season, she's worked up a doable translation of a jodhpur and also turned her attention to the new wide-legged satin pajama trouser of the Marlene-gone-modern kind. Something of the glam, playful, and luxurious has even filtered in along the way. There are cock-feather borders on vests, a hint of showgirl razzmatazz in the fringed shorts and flapper shifts, and, if you look very closely among the multiple chains strung around the models' necks, a few transparent lockets filled with crystalline grains that are actually real diamonds—evidence of Demeulemeester's first foray into fine jewelry.