Tim Walker is a listener, taking in conversational cues and stray bits of wisdom with a mind that whirs incessantly, much like the camera he carries wherever he goes.And that may be why, as he stood gazing seaward during a shoot last year on the northern coast of England, he was all ears when Kristen McMenamy, his model and muse, confided that she had long been enchanted by mermaids. She told Mr. Walker, as he recalled, “This is the one character I’ve never been able to play,” her wistful confession giving rise to a mutual, and mutually obsessive, fantasy.At the time, the customarily flame-haired Ms. McMenamy wore a silver-gray mane — perfect, she decided, for her imagined role. “I’m not going to cut it until I’ve done the mermaid,” she told Mr. Walker playfully. “So you’d better make it work.”Their shared vision eventually took shape in a series of eerily unsettling photographs that made their debut in the December/January issue of W. In the fashion portfolio, theoretically conceived to show off a selection of Vionnet dresses, Ms. McMenamy is seen immersed in a giant fish tank; seated at a vanity, a pearl ring through her nose; or resting her tail fin on a homely brass bed.That shoot was a high point in an annus mirabilis for the British photographer, 43. With the publication of two books, a flurry of high-profile advertising campaigns and a film in progress, he is, as he tells it, only now hitting his stride.The W shoot began haltingly, too sweet, or alternately too stilted, for his taste. But eventually shooter and model found their rhythm, the experience one of several this year that taught him, he said, “to simply let go, to give in to the uncontrollable force that leads you to do your best work.”Struck by the fluidity of Ms. McMenamy’s gestures in and out of water, he accompanied his stills with some seven minutes of Super 8 footage, unveiling his mini-film during Art Basel in Miami Beach earlier his month.An expanded version, now in the editing stage, is the extension of Mr. Walker’s natural proclivities. “His shoots, they don’t start with the clothes,” said Stefano Tonchi, the editor of W, who commissioned the photographs. “They start with an urgency for him to tell a story.”Which is part of what makes Mr. Walker, among fashion photographers, “the last romantic,” Mr. Tonchi said. In short, “not the kind of guy you can call and say: ‘I have 12 white dresses. Can you shoot them against a blank drop?’ ”Mr. Walker concurred. “I’m not so motivated by fashion and brands,” he acknowledged by phone from his studio in Brick Lane in East London. Apart from fantasists like the late Alexander McQueen and Rei Kawakubo of Comme des Garçons, he finds little in fashion to sustain him.“We’ve gone into a super-commercial moment,” he said. “There has never been more fashion, but it’s never been more bland.”Oddly, his tendency to obscure clothes in favor of elaborately staged, dreamy narratives has only endeared him to the art and fashion set. His works are in the permanent collections of the Victoria & Albert Museum and the National Portrait Gallery in London.His books, “Tim Walker: Story Teller,” with images like an outsize owl glowering in the corner of an ornate room, or a model dwarfed by a madly grinning doll; and the charmingly dotty “Granny Alphabet,” which introduces a parade of willfully eccentric old ladies, are among this year’s coveted coffee-table volumes. Luxury brands including Dior, Givenchy and Mulberry continue to sign Mr. Walker for ad campaigns, and his fashion work crops up regularly in W and in international editions of Vogue.True, his fairy-tale interpretations, sugary to the casual eye, can on close study seem downright menacing. “A fairy tale without darkness won’t resonate emotionally,” Mr. Walker said. He takes his own emotional cues from, among others, the spooky work of the 19th- and early 20th-century illustrator Arthur Rackham and uncanny fables of Hans Christian Andersen.“They get the balance of light and darkness right, and isn’t that the point,” Mr. Walker said.“Don’t forget, the Little Mermaid has to walk on broken glass.”