And the Bafta winner is...Helena Bonham Carter's mum

In Pictures: who wore what at Baftas 2011

Accepting the best supporting actress prize for her role in The King's Speech, she said there was "no doubt that, were my father alive, he would have given this to her".

As the drama, recounting how King George VI overcame his stammer, took seven awards, Bonham Carter said: "My dad [Raymond] was really disabled for the last 25 years of his life and mum was really extraordinary in tireless caretaking, and also looking for anything that would help him suffer less. She so genuinely qualified to be best supporting wife."

At the Orange British Academy Film Awards at the Royal Opera House, the 44-year-old also praised the late Queen Mother, who she plays in the movie, and admitted that playing royalty seemed to work for UK actors. It follow's Helen Mirren's success with The Queen, and Judi Dench's turns as Victoria in Mrs Brown and Elizabeth I in Shakespeare In Love.

The King's Speech won the rare double of best British film and best film; acting honours for Colin Firth as the king, Bonham Carter and Geoffrey Rush; original screenplay for David Seidler; and music for Alexandre Desplat. It has overtaken Slumdog Millionaire to become the most successful British movie at the UK box office.

Firth's best actor triumph made him the first since Dench to win Baftas back to back, after A Single Man last year, and boosted expectations of an Oscar. After his speech alluded to postponing "an uncomfortable medical examination" to discuss the role with director Tom Hooper, he later reassured fans it was a routine check-up. Also at last night's awards were Jessica Alba, Kevin Spacey, Samuel L Jackson, and rivals for best actress Julianne Moore and Annette Bening - both lost out to Natalie Portman.

Guests later partied at Grosvenor House. Firth, 50, was among a hardcore who left movie mogul Harvey Weinstein's private party at the new W London hotel in Leicester Square at 4am.

Bonham Carter's partner, director Tim Burton, saw his 3D hit Alice In Wonderland take costume and make-up awards. He presented Sir Christopher Lee with a Bafta fellowship, the Academy's highest honour. Tom Hardy was named Orange Rising Star.

Facebook drama The Social Network, regarded as The King's Speech's biggest rival, settled for three honours, including best director for David Fincher.

The stars and team behind the Harry Potter movies won an award for outstanding British contribution to cinema. Author J K Rowling led stars Emma Watson and Rupert Grint on stage - with Daniel Radcliffe absent on Broadway - to accept the prize from Stephen Fry. Grint said afterwards: "It's about time. We're all really chuffed."

Here is the full list of winners from the Bafta film awards:
ORIGINAL MUSIC: Alexandre Desplat for The King's Speech
SHORT FILM: Until The River Runs Red
SHORT ANIMATION: The Eagleman Stag
SOUND: Inception
EDITING: The Social Network
MAKE UP & HAIR: Alice in Wonderland
FILM NOT IN THE ENGLISH LANGUAGE: The Girl With The Dragon Tattoo
COSTUME DESIGN: Colleen Atwood for Alice in Wonderland.
PRODUCTION DESIGN: Inception
SPECIAL VISUAL EFFECTS: Inception
SUPPORTING ACTRESS: Helena Bonham Carter for The King's Speech
OUTSTANDING DEBUT: Chris Morris for Four Lions
OUTSTANDING BRITISH FILM: The King's Speech
SUPPORTING ACTOR: Geoffrey Rush in The King's Speech
ORIGINAL SCREENPLAY: David Seidler for The King's Speech
OUTSTANDING BRITISH CONTRIBUTION: The Harry Potter Films
ANIMATED FILM: Toy Story 3
ORANGE WEDNESDAYS RISING STAR: Tom Hardy
ADAPTED SCREENPLAY: Aaron Sorkin for The Social Network
CINEMATOGRAPHY: Roger Deakins for True Grit
DIRECTOR: David Fincher for The Social Network
LEADING ACTRESS: Natalie Portman for Black Swan
LEADING ACTOR: Colin Firth
BEST FILM: The King's Speech
FELLOWSHIP: Christopher Lee