Torrential rain greeted the stars on the red carpet for the Baftas.
Brad Pitt, Angelina Jolie and Kate Winslet braved the downpour for one of the biggest nights on the British film calendar.
Slumdog Millionaire leads the home hopes at the awards with 11 nominations, while Winslet is hoping to add to her two Golden Globes.
Winslet is up for Leading Actress for playing a former concentration camp guard in The Reader and also for her role in Revolutionary Road, which reunited her with Titanic co-star Leonardo DiCaprio.
Winslet, who has previously won a Supporting Actress Bafta for Sense and Sensibility, is also in the running for Best Actress for her role in The Reader at the Oscars, which takes place later this month.
Slumdog director Danny Boyle said the "extraordinary adrenalin" around the rags-to-riches tale had kept him going through six months of promoting the film.
"It's extraordinary the energy around the film," Boyle said. "We've been talking endlessly about it but there's an energy around it that's extraordinary."
Dev Patel, the film's 18-year-old star, brought his mother and sister to the glittering awards ceremony at London's Royal Opera House.
The nominations pit newcomer Patel against veteran actors such as Mickey Rourke for Leading Actor, following Rourke's powerful comeback in The Wrestler.
As well as facing competition from herself in the Leading Actress category, Winslet is also up against Angelina Jolie for Changeling, Kristin Scott Thomas for I've Loved You So Long and Meryl Streep for Doubt. Streep won a Leading Actress Bafta for the 1981 film The French Lieutenant's Woman.
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