The film continued its awards-show dominance, racking up seven awards, including Best Film.
But there was a movie that actually managed to upset the Slumdog juggernaut for the night's other main award: Man on Wire.
The documentary about the Frenchman who staged a secret high-wire walk between the two World Trade Center towers was the surprise winner of Outstanding British Film.
While Slumdog scored the lion's share of the prizes (distantly trailed by The Curious Case of Benjamin Button, which earned three), its cast failed to make an impact in the acting categories.
Though not on the speeches, thanks to Best Director winner Danny Boyle.
"David Lean said you should announce your ambition for the film in the first five minutes," Boyle said. "In that spirit, I'd like to announce my ambition for this speech: My father's power went out last night. A big shout-out to everyone who helped him run the extension cable in so he could watch this tonight."
As for Winslet, the actress kept her speech brief, possibly to avoid a repeat of her post-Globes tongue-lashing from her stiff upper-lipped countrymen.
"Thank you very, very much," she said. "To get this award at home, this really means a great deal to me. Thank you, BAFTA."
Winslet also thanked her "mum and dad," who were in the audience, but said she couldn't look at them during her speech as she would likely "burst into tears."
"I want to thank Anthony Minghella and Sydney Pollack. You are much missed today, and you will be much missed for years to come."
Meanwhile, joining Winslet in the winner's circle was Vicky Cristina Barcelona's Penélope Cruz, who took home the Supporting Actress prize, The Dark Knight's Heath Ledger, who continued his posthumous domination in the Supporting Actor category and The Wrestler's Mickey Rourke, who walked away with the Lead Actor nod.
"It's a pretty statue," Rourke said, before thanking director Darren Aronofsky for giving him a second chance despite his having "f--ked up [his] career for 15 years. Such a pleasure to be here and be out of the darkness."
While Rourke did not thank his dogs this time around, he did remember to thank costar Marisa Tomei for "being brave enough to take your clothes off all the time."
Aw, he shouldn't have.
Surprisingly, Slumdog Millionaire and The Curious Case of Benjamin Button were the only films of the night to score multiple awards.
Here's the complete list of winners for the 2009 Orange British Academy Film Awards:
- Best Film: Slumdog Millionaire
- Outstanding British Film: Man on Wire
- Director: Danny Boyle, Slumdog Millionaire
- Leading Actor: Mickey Rourke, The Wrestler
- Leading Actress: Kate Winslet, The Reader
- Supporting Actor: Heath Ledger, The Dark Knight
- Supporting Actress: Penélope Cruz, Vicky Cristina Barcelona
- Original Screenplay: Martin McDonagh, In Bruges
- Adapted Screenplay: Slumdog Millionaire
- Animated Film: WALL-E
- Film Not in the English Language: I've Loved You So Long (France)
- Music A.R. Rahman, Slumdog Millionaire
- Editing: Slumdog Millionaire
- Cinematography: Slumdog Millionaire
- Production Design: The Curious Case of Benjamin Button
- Costume Design: The Duchess
- Sound: Slumdog Millionaire
- Special Visual Effects: The Curious Case of Benjamin Button
- Makeup & Hair: The Curious Case of Benjamin Button
- Short Animation: Wallace & Gromit: A Matter of Loaf and Death
- Short Film: September
- The Carl Foreman Award (special achievement for first feature film): Steve McQueen, writer-director, Hunger
- The Orange Rising Star Award (voted for by public): Noel Clarke
- Academy Fellowship: Terry Gilliam
- Outstanding British Contribution to Cinema: Pinewood Studios/Shepperton Studios