Daniel Day-Lewis has a reputation for inhabiting his film characters totally, in mind, body, and spirit. And for Reynolds Woodcock—the fictional, fastidious couturier at the center of Paul Thomas Anderson’s Phantom Thread—Day-Lewis was even more invested than usual. He created the character with Anderson and even came up with the designer’s name. While Anderson was writing the script, Day-Lewis studied fashion, learning how to cut, drape, and sew—and even re-created a Balenciaga dress on his own.

So when Anderson’s longtime collaborator, Oscar-winning costume designer Mark Bridges (The Artist) began work, Day-Lewis already knew how the exacting Woodcock would dress.

“Daniel knows the world of bespoke,” Bridges told Vanity Fair, pointing out the actor’s background—he grew up in the affluent neighborhood of London's Kensington, as the son of poet Cecil Day-Lewis. “I’ve discovered, while studying for this film and of course working with Daniel, that it’s not unusual for men of a certain status in England to be concerned and aware of their wardrobes. A gentleman would think about the placement of a buttonhole or a kind of fabric.”

Day-Lewis plucked costume inspiration from people familiar to him, choosing Reynolds’s suits, for example, from Anderson & Sheppard, the Savile Row clothing house established in 1906 that dressed Day-Lewis’s father (as well as Cary Grant and Prince Charles). When Bridges and Day-Lewis went to Anderson & Sheppard during one of their wardrobe quests, Bridges noticed that Day-Lewis’s own father, wearing his Anderson & Sheppard best, was featured in a book inside the historic store.

“Daniel would refer to people in his life, like we knew gray-flannel slacks would be right because his grandfather always wore the gray flannel with his country clothes,” Bridges said. ”He knew people who wore their Anderson & Sheppard country blazers“—as Reynolds does at his country house—“for years and years and years. There was a lot of him bringing his knowledge of that English wear to the table, and then us working together to make the pieces feel right for our film and to make sure they were photogenic.”

On several days, when Day-Lewis had breaks in his schedule, he and Bridges went shopping together in Mayfair—meeting at Drake’s haberdashery or Hilditch & Key to peruse ties. At Budd Shirt Makers, Day-Lewis handpicked a pair of lavender pajamas off the rack—which his character wears in several memorable scenes—as well as a blue pair with red piping. Bridges called the shopping excursions “really fun . . . a highlight of the process.”