Director Ken Loach's gritty I, Daniel Blake, a stinging critique of Britain's welfare system, was up for five awards.
La La Land was the big victor from the BAFTAs, picking up five gongs, including best film, director and leading actress for Emma Stone.
La La Land has been an enormous awards season success for the Whiplash director, with no less than 14 Academy Award nominations and several Golden Globes in the bag already.
Casey Affleck won the best actor award for his performance in "Manchester By the Sea".
Affleck said he learnt to act while attending therapy sessions for children of alcoholics.
Kenneth Lonergan's screenplay won "Manchester by the Sea" a second award.
The BAFTAs differ from their U.S. counterpart in having a separate category for best British film.
Prince William, who is also president of Britain's film academy, was to present the academy's lifetime-achievement honor to veteran comedian Mel Brooks during Sunday's ceremony.
He continued: "Anybody who would think of voting Labour but then changes to Ukip should really look at this because if Ukip and the far right get in this will get worse". The ceremony will take place at the prestigious Royal Albert Hall where celebrities in movies will come together at the big night.
"I especially like it in a profession that could be considered narcissistic. We do, we're rebels, we make political statements", she told AFP, before picking up the best supporting actress award for "Fences".
BAFTA 2017 Awards Nominations for Best Actor in a Supporting Role are - 1) Mahershala Ali - Moonlight as Juan 2) Jeff Bridges - Hell or High Water as Marcus Hamilton 3) Hugh Grant - Florence Foster Jenkins as St. Clair Bayfield 4) Dev Patel - Lion as Saroo Brierley 5) Aaron Taylor-Johnson - Nocturnal Animals as Ray Marcus.
"I'm just so happy he's the leading man now and that he's been given the platform to become a leading man, and he's taking it with a vengeance and I'm so happy for him".