We Need to Talk About Kevin, an unflinching portrayal of a mother's troubled relationship with her son starring Oscar winner Tilda Swinton, won the London film festival's best picture award on Wednesday.
The movie, which impressed critics when it premiered at the Cannes film festival in May, was directed by Scottish film maker Lynne Ramsay and based on Lionel Shriver's award-winning novel of the same name.
We Need to Talk About Kevin was one of nine best film nominees at London's annual cinema showcase, and beat Venice winner Faust and The Descendants starring George Clooney, among others.
In the end, we were simply bowled over by one film, a sublime, uncompromising tale of the torment that can stand in the place of love, said John Madden, chair of the judging panel. 'We Need to Talk About Kevin' is made with the kind of singular vision that links great directors across all the traditions of cinema.
The British newcomer award went to actress Candese Reid for her work in Junkhearts, her first professional acting role.
The Sutherland Award, honoring the most original and imaginative feature debut at this year's festival, was won by Argentinean director Pablo Giorgelli for Las Acacias.
And the Grierson Award for best documentary went to Werner Herzog's death-row examination Into the Abyss: A Tale of Death, A Tale of Life.
As previously announced, Canadian director David Cronenberg and British actor Ralph Fiennes were awarded the BFI Fellowship, the British Film Institute's highest accolade.
This year's festival closes on Thursday with a gala screening of The Deep Blue Sea, Terence Davies' adaptation of Terence Rattigan's play starring Rachel Weisz.