"I think the most important thing with all of this is speaking out and being seen to speak out", said Amanda Nevill, chief executive of the British Film Institute.
He said the same could be true of its star Frances McDormand, who plays Mildred, a woman with a burning sense of injustice over the police failure to find the killer of her daughter. Men showed solidarity with Time's Up lapel pins as tremors from abuse revelations rumble through the movie awards season.
Who will win at the 2018 BAFTAs?
"Darkest Hour" has also been nominated in the best film and outstanding British film categories, while Kristin Scott Thomas is up for supporting actress for her role as Churchill's wife Clementine.
Princess Kate accompanied William, who is president of BAFTA, and also wore a glittering matching emerald and diamond necklace to the Awards ceremony.
"Three Billboards" won five awards, including best film, best actress for its lead performer Frances McDormand and a supporting actor award for Sam Rockwell.
Allegations of sexual harassment and abuse have been leveled at scores of entertainment figures since women began coming forward to accuse Hollywood producer Harvey Weinstein a year ago.
In the last seven months, Hollywood and the entertainment industry has been wracked with assault, harassment, and rape allegations with the downfall of many prolific stars such as Kevin Spacey, Louis CK, Weinstein, James Toback, Jeremy Piven, and many more.
Guillermo del Toro won the directing prize for monster fantasy "The Shape of Water", which also took trophies for music and production design.
They posted on Twitter: "We just crashed the #EEBAFTAs red carpet to say #TimesUpTheresa: your DV bill is a risky distraction from what we really need, funding for refuges and specialist domestic violence services".
Nonetheless, she said she stood in full solidarity with her sisters and finished her acceptance speech with the words: 'Power to the people'. "As Martin said I have a little trouble with compliance", she said as she acknowledged her brightly-printed dress, a departure from the sea of black gowns and tuxes worn in a nod to the movements.
The Duchess of Cambridge wore a dark green dress with a black ribbon belt.
Ahead of the ceremony, nearly 200 British female entertainment stars called for an worldwide movement to end sexual misconduct.
Former "Harry Potter" star Watson has given the fund 1 million pounds (USD$1.4 million), according to its page on the Go Fund Me website.
But all three are up for the best overall film award, along with Christopher Nolan's own second world war drama Dunkirk, and Luca Guadagnino's coming-of-age romance Call Me By Your Name.
Ridley Scott, whose films include "Blade Runner", "Alien", "Thelma and Louise" and "Gladiator", is set to receive the academy's highest honor, the BAFTA Fellowship.
Oldman said the prize is "all the more special because I can share it with my family", including his three sons in the London audience.