Simon Channing Williams, a film producer whose partnership with the director Mike Leigh resulted in a string of quirky, critically praised films, including “Secrets and Lies” and last year’s “Happy-Go-Lucky,” died last Saturday in the county of Cornwall, England. He was 63.

The cause was cancer, Leigh told the BBC.

Leigh and Channing Williams (at some point in his career he disposed of a hyphen in his surname) formed Thin Man Films in 1988, the company name a jokey reference to the ample girth of both men. Under its aegis, they turned out a number of character-based films, usually depicting the lives of ordinary, working-class people, though one of their most successful collaborations, “Topsy-Turvy” (1999), was a rollicking portrayal of the musical partnership of Gilbert and Sullivan.

The titles included “Life Is Sweet” (1991), a portrait of an oddball family in north London; “Naked” (1993), about the scabrous behavior of a heartless seducer; “Vera Drake” (2004), a morally complicated story of a loving family woman who also performs illegal abortions; and “Happy-Go-Lucky,” about a young woman’s upbeat striving against a mundane existence.

Their most successful collaboration, “Secrets and Lies,” about a white woman who is reunited with the half-black daughter she gave up as an infant, won the top prize at the 1996 Cannes Film Festival and was nominated for five Academy Awards, including best picture.

Channing Williams was born on June 10, 1945, in Maidenhead, Berkshire, England. As a young man, he wanted to be an actor. He began his film career in the 1970s at the BBC, where he was an assistant director on television projects that included the 1980 BBC2 Playhouse production “Grown-Ups,” written and directed by Leigh.

In 1987, Channing Williams was a producer of “The Short and Curlies,” a short film for television directed by Leigh, and before starting Thin Man, they also made “High Hopes,” a comedy of manners set in the lower middle class of Margaret Thatcher’s England.

In addition to his work with Leigh, Channing Williams also had another film company, Potboiler Productions, started in 2000. That company produced, most notably, “The Constant Gardener” (2005), a murder mystery set against a backdrop of corporate corruption in Kenya. Adapted from the novel by John le Carre, it was directed by Fernando Meirelles and starred Ralph Fiennes and Rachel Weisz.

The movies themselves, often caustic and humanistic in equal measure, tartly humorous and morally ambiguous, could never be called easy sells.

“He was a natural-born producer, a great leader, always an enabler, a protector,” Leigh wrote of Channing Williams in the London newspaper The Guardian this week, “never a dictator or an interferer.”