Unflinching drama 12 Years a Slave has won the best-picture prize at the British Academy Film Awards, while its star, Chiwetel Ejiofor, has been named best actor.
Ejiofor thanked director Steve McQueen for bringing to the screen the true story of a free black man kidnapped into servitude in the 19th-century American South.
Holding the trophy on Sunday, he told McQueen: "This is yours. I'm going to keep it - that's the kind of guy I am - but it's yours".
The best-actress prize went to Cate Blanchett for her turn as a socialite on the slide in Blue Jasmine. She dedicated the award to actor Philip Seymour Hoffman, who died this month.
Alfonso Cuaron was named best director for Gravity - one of a clutch of prizes for the sci-fi thriller, including best British movie.
Made in the UK by Mexican director Alfonso Cuaron and starring Sandra Bullock and George Clooney, Gravity has 11 nominations in all for Britain's equivalent of the Oscars, and is a favorite to take the overall best-picture prize.
David O. Russell's con-artist caper American Hustle and 12 Years a Slave are the other front-runners, with 10 nominations apiece.
The temperature was hardly Hollywood, but Britain's fickle weather relented ahead of Sunday's ceremony. The sun shone as nominees including Wolf of Wall Street star Leonardo DiCaprio and 12 Years a Slave performer Lupita Nyong'o- striking in a green Dior gown - walked the red carpet outside London's Royal Opera House.
Best-actress nominee Amy Adams wore a black dress by Victoria Beckham, and revealed the inspirations for her American Hustle character's faux-British accent: "Marianne Faithfull and Julie Christie".
There was royalty of the Hollywood kind - Brad Pitt and Angelina Jolie, wearing matching tuxedos. And there was British royalty, too, in the form of Prince William, honorary president of the film academy.
In the past few years, the prizes, known as BAFTAs, have helped underdog films, including Slumdog Millionaire, The King's Speech and The Artist, gain Oscars momentum. This year, bookmakers have made 12 Years a Slave, which has a British director and a British star, Chiwetel Ejiofor, favorite to take home the best picture and best actor trophies.
Director McQueen said he was "so proud" to be nominated for awards in his home town, London. And he paid tribute to Brad Pitt, a producer on "12 Years," for helping to get the film's uncompromising vision of slavery onscreen.
"If you're trying to make a movie like this, you need some heavy backers," McQueen said. He said slavery "happened because of mental violence and physical violence. One has to be honest and truthful".
The BAFTAs have become an essential stop for many Hollywood stars ahead of the Academy Awards, held this year on March 2.
Nominees Bradley Cooper, Matt Damon, Cate Blanchett, Judi Dench and Sandra Bullock were among those attending Sunday's black-tie ceremony.
This year's best-picture nominees are: 12 Years a Slave; Gravity; American Hustle; Captain Phillips; and Philomena, the story of an Irishwoman in search of the son she lost decades earlier.
The separate category of best British film pits Gravity,Philomena and Mary Poppins story Saving Mr. Banks against motor-racing drama Rush, biopic Mandela: Long Walk to Freedom and gritty parable The Selfish Giant.
Helen Mirren is to receive the British Academy Fellowship in honor of a career that has ranged from a hard-nosed detective in TV series Prime Suspect to Queen Elizabeth II in The Queen.
Mirren, who won a best-actress Oscar for The Queen, said she had never expected to get the honor, whose previous recipients include Charlie Chaplin, Alfred Hitchcock, Elizabeth Taylor and Judi Dench.
"I always imagined myself as a bit of an outsider, really, sort of the naughty girl," Mirren said.
Mirren, 68, is no stranger to awards, but she said the prospect of making Sunday's acceptance speech was daunting.
"You think, 'My God, I've got to talk about my whole life,'" she said. "Not only my whole life - what movies mean, what movies mean to me, what they mean to all of us. And do it all in two minutes."