The actress, who sat on the 2009 jury alongside singer Jarvis Cocker, handed the Star of London prize to lead actor Tahar Rahim, who plays a young man in a crime-ridden prison, at the festival's closing ceremony in the British capital.
Huston hailed the drama as "a masterpiece (with) the ambition, purity of vision and clarity of purpose to make it an instant classic".
Meanwhile 69-year-old British actor John Hurt was honoured with a lifetime achievement award known as the British Film Institute Fellowship.
The star says, "For me, the BFI is the heart of British cinema. I consider it the highest honour possible to be awarded a Fellowship."
The 53rd London Film Festival closes on Thursday (29Oct09) with a screening of Nowhere Boy, artist Sam Taylor-Wood's film about Beatles legend John Lennon.