"[Suffragette] was a really important - if not the most important - job that I've ever done," she says.
"I felt incredibly privileged, considering it took 100 years for this story to get told. I just really wanted to mark the moment." The story that the film tells is not one that's especially well known.
Say "suffragette" and most people probably conjure up pictures of demure marchers carrying "Let women vote" signs or testifying before Parliament. But Suffragette focuses instead on a more radical wing of the movement: the Women's Social and Political Union (WSPU).
Led by Emmeline Pankhurst (Streep), the group advocated such acts of civil disobedience as arson, mailbox bombings, window smashing and vandalism of artworks. In response, many women were jailed and, when they went on hunger strikes, were subjected to force-feeding or beaten. Some died of their injuries.
That darker chapter has been "written out" of history books, according to Gavron, who worked with Morgan for six years on the Suffragette screenplay.
Bringing this violent struggle to light is not just overdue, Gavron says, but "really timely", considering what the film-maker calls the ongoing repression of women by the Taliban, Boko Haram and the Saudi government, which has only recently begun registering women to vote. (They still have to be driven to the registration centres by men, Gavron notes, since Saudi women are not allowed to drive.)
Though Suffragette portrays Streep's Pankhurst as a powerful, prominent figure - albeit one who is in hiding for much of the film - its narrative centres around Maud, a begrimed washerwoman with a working-class husband (Ben Whishaw) and young son (Adam Michael Dodd). Maud is reluctant to join the WSPU until a galvanising incident: Her husband kicks her out of the house and puts their son up for adoption.
"A friend of mine who recently had a baby was furious with me for not warning her about that scene," says Mulligan, who gave birth in September to daughter Evelyn. (She is married to Marcus Mumford, of the band Mumford & Sons.) "It's horrendous to think, but women had no parental rights over their children. It was commonplace for women to lose their children, or for women - amazingly - to be committed to mental institutions simply for becoming suffragettes," as supporters of women's voting rights - suffrage - came to be known, after a derisive nickname first used in a 1906 Daily Mail newspaper article.
The suffragettes of the WSPU - as opposed to the more staid and non-violent wing known as suffragists - were "really clever", according to Mulligan, who calls their use of branding ahead of its time.
"They were incredibly strategic in what they did, and reappropriating the word 'suffragette' as a term of empowerment was just part of that." Like Gavron, Mulligan believes that the film's message of equality is timely. The actress recently spoke out in support of Jennifer Lawrence, who recently wrote an essay on the gender gap in Hollywood movie salaries.
As for Gavron, she laments that, even in a season rife with movies about strong women - she rattles off Carol, Brooklyn and Room, to name a few - all of those films, it turns out, were directed by men.
"This [year's] London Film Festival - which sought out films by women - presented 46 woman-directed movies," says Gavron. "And that was still only 19 per cent of the 240 films shown." The director is quick to point out that Suffragette is not a political screed.
Rather, she says, it is a personal story filtered through the lens of politics. At 45, Gavron says that she came of age during the "first post-feminist wave" of the 1980s. She says she understands why many of today's young women - women of Mulligan's generation - resist calling themselves feminists.
"That term is mired in a past incarnation. Young people are eager to have their own word for it." Mulligan doesn't think it matters what label supporters of women's rights use to describe themselves. She cites Pankhurst's WSPU motto of "deeds not words" in defence of Streep, who recently came under fire for commenting that she considers herself a "humanist" rather than a feminist.
"People have been saying, 'Well, she's denying being a feminist,' which is nonsense," Mulligan says. "Her actions speak for herself. She's been the biggest advocate of women's rights her entire career and continues to be. Whatever word you choose, the intention behind it seems to be the same for most women my age."
Mulligan doesn't hesitate to call herself a feminist. As she promotes a film that is both a history lesson and a reminder of how far women have yet to go in the struggle for equality, she says that she's delighted to talk about something other than the standard Hollywood "white noise".
"The most positive aspect of Suffragette is that I've been able to do interviews like this one, where I get to talk about interesting things for a change. A lot of the time, all I talk about is wearing pretty costumes or kissing whatever male co-star I'm in the film with. That's been a relief and kind of great."
