For producer Graham King, the mathematics of the movie business is easy — it all hinges on the sum of your relationships.

In his keynote sesh at Friday’s BritWeek Film and TV Summit, King emphasized that the long-term working partnerships he’s developed has been crucial to his success during the past 15 years.

As an example, he noted that backing Johnny Depp’s passion to play Hunter S. Thompson in “The Rum Diary” led his GK Films to team with Warner Bros. on “Dark Shadows.” (King was effusive about how the pic turned out and said there’s already talk of “Shadows” sequel.)

His work on “The Tourist” led Angelina Jolie to bring him her directorial debut, “In the Land of Blood and Honey.” And Sacha Baron Cohen approached him, on the set of “Hugo” with the pitch that he would love to play Queen frontman Freddie Mercury in a biopic.

And of course, the cornerstone of GK Films has been King’s fruitful relationship with “Hugo” helmer Martin Scorsese.

“Without him, I’m not sitting here right now,” King said in the Q&A with Variety editor-in-chief Tim Gray at Century City’s InterContinental Hotel. He recalled their first meeting at the Beverly Hills Hotel as King was helping to get foreign coin for “Gangs of New York.” What was supposed to be a half-hour sesh turned into a five-hour discussion.

King said gravitates to movies that intrigue him and his creative partners, and rarely takes a traditional pitch from agents or packages. Among his passion projects at the moment is his plan for an “all-star” remake of the WWII movie “The Battle of Britain,” with Robert Towne now working on the script.

He’s happy to stay out of the tentpole biz, though he did note that “Dark Shadows” is his first four-quadrant project.

“I’m not a comicbook guy,” King said. “I appreciate what the studios do. They’ve kept me in business by not greenlighting the kind of movies I do.”

King said he’s found it very satisfying to back the vision of talented people, especially those looking to grow, as Ben Affleck did in helming “The Town” and Jolie did with “Blood and Honey.”

“I get very excited about being able to give birth to someone’s new career,” he said.

In the wide-ranging convo, King offered keen observations on the film marketplace on both sides of the Pond. He finds it “sad” that because of the lack of significant production tax incentives in the Golden State, it’s so hard for indie producers to lense in Hollywood. Of all his films, the only time King has shot in California was a two-week frame in Santa Barbara on “The Aviator.” Even with the exchange rate and travel costs, “it’s much cheaper for me to shoot a movie in London,” he said.

But in his view, the U.K. film biz itself needs to start thinking bigger about the scope and international appeal of homegrown pics. He joked that producers have a tendency to think: ” ‘Oh my god, we’re British, let’s make a small movie.’ ” He was surprised a few years ago when he couldn’t get any U.K. government funding for the Emily Blunt-Rupert Friend costume drama “The Young Victoria.” “But if I wanted to make a movie about two guys at a bus stop in Wolverhampton, they’d fund that,” he quipped.

What’s more, his native city of London is definitely in need of new studio facilities, King said. While shooting “Hugo” at Shepperton Studios, he and Scorsese took to calling the lot “Stalag 17.”

Although the volume of his business has grown in recent years, and he’s branched out into TV series, King said it’s still important for him to have a personal connection to the projects he backs.

“I don’t want to be in (a production) just for it to be a piece of business,” he said. “Why else would I spent two years working my butt of to bring it to the screen? You have to emotionally attached.”

Earlier in the day, a clutch of international film biz players expressed optimism about a rebound in the market for indie pics with strong commercial potential.

“It’s feast or famine with independent projects,” said IM Global topper Stuart Ford. “If the movie deserves to get made, then the foreign market is as strong as it ever was.”

Nigel Sinclair, CEO of Exclusive Media, said he feels there’s great opportunity in the U.S. right now because of the hangover affect from the economic crisis, when buying activity virtually ceased for about 18 months. “I think (the U.S.) is a very under-sold market right now,” he said.

During a later sesh focused on TV, panelists couldn’t help but talk about the “Downton Abbey” phenomenon and its resonance in the U.S. BBC Worldwide Prods. chief Jane Tranter observed that “Mad Men” helped whet domestic appetite for period fare. And the hoopla over last year’s wedding of Prince William and Kate made the moment just right for a good sudsy British costume drama.

“It’s always about the cultural moment when the show hits,” Tranter said. “It’s absolutely glorious thing when you see it happen.”

Despite much speculation to the contrary, Gareth Neame, with NBCUniversal Intl.’s U.K. production wing and a “Downton” exec producer, said that there was no advance plan to make Elizabeth McGovern’s character an American to make the show more palatable to Yanks.

“If (‘Downton’) hadn’t worked in the U.S., it really wouldn’t have mattered,” he said.