Over the summer, Clare Waight Keller had a good look at Pringle's archives, where she found the late 1950's and early 1960's particularly well represented—and particularly inspirational. It was a critical moment in U.K. culture, the point where the austerity of the war years tipped into the freedom of the sixties. Picture David Bailey's first photos of then-girlfriend Jean Shrimpton, or bad girls Christine Keeler and Mandy Rice-Davies showing up for their court appearances looking very proper for such naughty young women.

Those were the kind of images in Waight Keller's mind. If the grown-up, "even granny" clothes of the era posed a theoretical challenge to her brief to bring Pringle into the twenty-first century, the creative director rose to the task with her sharpest collection to date, one which brought together the house's heritage, her instinct for innovation, and her eccentric little twists of Celtic pomp. All three elements were present in a gilet paneled in lacquered beaver and tufted with cashmere and tweed interwoven by hand. The piece had an almost savage allure, like something Lady Macbeth might don to seduce and then slaughter a Highland laird. Not for everyone, in other words.

But you could easily imagine Waight Keller's lean little shifts finding an appreciative audience. The small curved shoulder and narrow sleeve were straight from the archives, but the abbreviation felt contemporary. A sleeveless version—knitted in a diamond jacquard found in the menswear archives and zipped up over a top and worn with knee-high boots—looked like a right-now take on Pringle's classic argyle twinset, though it also wasn't hard to imagine the Shrimp in the same thing. Same with a luxe angora.

Waight Keller's facility with knits means that updating tradition comes easily to her. When she talked about modernizing "the granny element," she could well have meant a tweed coat given a 3-D raffia effect, or a cashmere sweater veiled in a diaphanous herringbone, or the jacket and skirt that combined alpaca and rabbit for a hand as soft as feathers. And that iconic twinset, Elizabeth II's fave, has been reconfigured and spun off as a separate capsule collection. The Queen will still find her classic cashmere sweater and cardie combo in 12 colors, but Waight Keller also offered a twinset in black wool lace, and another in coral paillettes that might pique the interest of the royal granddaughter-in-law-to-be.