The star of the film, Imelda Staunton, was crowned best actress at the Evening Standard British Film Awards, following in the footsteps of past winners, Dame Maggie Smith, Glenda Jackson and Emma Thompson.
Leigh's film is Britain's greatest hope for a prize at this year's Oscars ceremony, where it is nominated in three categories: best actress, best director and best screenplay.
The critically acclaimed film has also been nominated in 11 categories for next week's Baftas, where Staunton is tipped to win best actress.
The film, about a kind-hearted cleaner who is arrested when her secret trade as an illegal abortionist is discovered, swept the board at the British Independent Film Awards last year, winning six awards including best film and best director. It also dominated at the Venice Film Festival, where it won the Golden Lion for best film and best actress for Staunton.
The award for best actor went to Paddy Considine for his role in Dead Man's Shoes as a former soldier who returns to his village after seven years and seeks revenge on his brother's bullies.
Simon Pegg, the comedy actor who co-wrote and starred in the spoof horror film Shaun of the Dead, won the Peter Sellers award for comedy.
My Summer of Love, Pawel Pawlikowski's adaptation of Helen Cross's novel about a teenage lesbian romance, set in Yorkshire, won best screenplay. The film's stars, Emily Blunt and Nathalie Press, jointly won the prize for most promising newcomer.
A special award recognising contribution to the film industry, which was named after the Standard's long-serving film critic, Alexander Walker, went to Tim Bevan and Eric Fellner, co-chairmen of Working Title, the production house behind such hits as Four Weddings and a Funeral and Bridget Jones.
Other prizes included an award for technical achievement won by cinematographer Roger Deakins for his work on M Night Shyamalan's The Village, and the Coen brothers' remake of the 1950s comedy The Ladykillers.
Renee Zellweger won the readers' award for her reprisal of the lead role in the popular sequel, Bridget Jones - The Edge of Reason.Reuse content