Upbeat musical La La Land has triumphed over gritty dramas at the 70th EE British Academy Film Awards.
Gilbert has said he knows he's done a good job when nobody notices. Comedian and actor Stephen Fry will be hosting the ceremony for the 12th time.
Other winners included USA prison system film 13th for best documentary, and Lion's screenwriter Luke Davies for adapted screenplay.
The 80-year-old director used his acceptance speech at Britain's equivalent of the Oscars to lambast the country's Conservative government.
Stars that are confirmed to attend include: Lin-Manuel Miranda, Penelope Cruz, Emma Stone, Ryan Gosling, Meryl Streep, Viola Davis, J.K. Rowling, Andrew Garfield, Nicole Kidman, Daisy Ridley and Jamie Dornan.
The event also features other top nominations such as "Fantastic Beasts And Where To Find Them" for Outstanding British Film, an expected deadlock for the Award for Best Actress in a Leading Role between Emily Blunt for her role in "The Girl On The Train" and Emma Stone in "La La Land", and between Jake Gyllenhaal in "Nocturnal Animals" and the heart-throb Ryan Gosling for the Award for Best Actor in a Leading Role. Streep is among the stars who have used the awards stage to criticise President Donald Trump.
For Best Film the following works are nominated: "Arrival", "I, Daniel Blake", "La La Land", "Manchester By The Sea" and "Moonlight".More news: The Batman Solo Movie Scores New Director in Matt Reeves
He said: "I look at row after row of the most overrated people in the audience".
She said: "What (August) did is, is that he said our lives mattered as African Americans: the horse groomer, the sanitation worker, the people who grew up under the heavy rule of Jim Crow".
Prince William will present Mel Brooks with the Bafta Fellowship during the event.
"The philosophical sci-fi yarn Arrival" and the psychological thriller Nocturnal Animals have nine BAFTA nominations each.
I, Daniel Blake - which won the coveted Palme D'Or at Cannes previous year - chronicles the failings of the benefits system in the UK.
Leading actor went to Casey Affleck for Manchester By The Sea, which also won original screenplay for its writer and director Kenneth Lonergan.