After their much-acclaimed collaboration on “There Will Be Blood,” as well as lesser-known projects “The Master” and “Inherent Vice,” director Paul Thomas Anderson and Radiohead’s multi-instrumentalist savant Jonny Greenwood have teamed up for the fourth consecutive time on “Phantom Thread.”

The film’s piano-and-strings dominated score, which received a Golden Globes nomination for best original score, plays a key role in defining the lead characters of Reynolds Woodcock (Daniel Day-Lewis), the 1950s London couture designer, and Alma (Vicky Krieps), his model and lover. Anderson first called Greenwood about it a year ago.

“We talked a lot about ‘50s music, what was popularly heard then as well as what was being written and recorded,” Greenwood tells Variety. “Nelson Riddle and Glenn Gould’s Bach recordings were the main references. I was interested in the kind of jazz records that toyed with incorporating big string sections, Ben Webster made some good ones, and focus on what the strings were doing rather than the jazz musicians themselves.”

Greenwood reasoned that if Reynolds listened to music, it would have been Gould. “Lots of slightly obsessive, minimal baroque music,” says Greenwood. “And we could use the piano as the common ground between the romantic music and the formal, slightly more buttoned-up themes that suited Reynolds.”

The romantic movements “couldn’t cross into pastiche, or be in any way ironic,” he says. “It took a long time to figure out how to do that.” At one point, Greenwood recorded with an ensemble of 60 strings, his largest ever.

Some of the cues, however, are played by only a quartet. “The smaller groups, and solo players, work like close-ups [and] not necessarily to accompany [a] visual, but rather, to focus your attention on and make you feel directly engaged with the characters. The bigger orchestral things often worked best for drawing you back to see the bigger situation.”

Anderson first heard Greenwood’s themes-in-progress at the musician’s London studio.

“These were turned into a whole body of work for him to draw from, and to request longer, shorter, faster versions and variations,” says Greenwood, adding that, “Some cues were written specifically to scenes. Others were just sketches of the characters, or of the story.”

All told, some 90 minutes of music ended up in the final cut. Says Greenwood: “When I told [this to] Robert Ziegler, who conducted the score, he said, ‘That’s not a soundtrack, that’s a musical!’ But I know I’m pretty lucky to work on films like this, where there’s so much scope for developing a score over such a long time.”