In 1968, London may have been swinging, but Dagenham, England was sweltering. The 187 women working in the machinists section of the Ford automobile plant would strip to bras and slips to deal with the heat as they stitched together upholstery for car seats. It wasn’t easy work, but because Ford had recently re-classified it as unskilled labor, the small core of women workers received the lowest wages at the factory.

That’s the precipitating factor for “Made in Dagenham,” directed by Nigel Cole (“Calendar Girls”), which begins by establishing a groovy vibe, accompanied by a montage of period clips and opening credits. The women are under pressure, like every other low-wage factory worker in the world, and they’ve made their complaints known to the plant’s management, via union representative Albert (Bob Hoskins). They’ve been threatening to walk out over the issue.

Shop steward Connie (Geraldine James), distracted by problems at home — her husband George (Roger Lloyd Pack) is slowly slipping into senility — has come to rely upon her friend and co-worker Rita (Sally Hawkins) for emotional support, and so asks her along for a meeting with company executives. The men, led by Peter Hopkins (Rupert Graves) are dismissive, and union leader Monty Taylor (Kenneth Cranham) is acquiescent; he’s more concerned about maintaining civil relations with the company so as to negotiate better deals for the overwhelming male majority.

Sitting quietly up to that point, Rita can’t help but call “bullshit” on the proceedings. She’s incensed at the patronizing attitude shown for the women’s point of view, to the surprise of all present, and informs the Ford execs that the women will walk out if their demands are not met. And that’s exactly what happens; at Connie’s urging, it’s Rita who stands up and tells the women that they are on strike. Everyone cheers as they shut down their machines and march outside, making signs and standing proudly in front of the gate.

The strike is only meant to last a day, to show they mean business, but it doesn’t really achieve anything concrete. Rita wonders if symbolic actions will really make any difference at all. And then Albert has a talk with her. He encourages her to step up to the plate, arguing that Connie isn’t in a position to lead the battle. Raised by a single mother, he’s well aware of the inequities of the pay system, whereby women are paid only a fraction of what men are paid for the same work.

Reluctantly, and with Connie’s blessing, Rita leads the women in a prolonged labor action. Her husband Eddie (Daniel Mays) is supportive and willing to pitch in, mostly because he knows he should, but it’s not easy for him to take a more domestic role in a household that includes three children, especially when Rita begins traveling more.

That comes about because the strike has a ripple effect, eventually affecting the entire factory in Dagenham. As it spreads and other unions join in support, Ford’s automobile production grinds to a halt, prompting execs in Detroit to send hard-nosed Robert Tooley (Richard Schiff) in to solve the problem.

The strike has an affect on the women as well. Pressed into her leadership position, Rita finds that she quite enjoys expressing her point of view and rallying others to support “doing the right thing.” Others have a harder time of it. Connie begins to feel alienated from Rita, while friends Brenda (Andrea Riseborough) and Sandra (Jaime Winstone) start to question the value of the strike. Can a small group of women possibly effect the kind of historic changes that “equal pay for equal work” would entail?

Two other women figure into the story. Lisa Hopkins (Rosamund Pike), the wife of Ford exec Peter, quietly admires Rita for what she’s doing, and so does Barbara Castle (Miranda Richardson), a high government official who’s tired of being minimized herself, thank you very much, yet has a politician’s instinct for survival.

The film’s lighter tone becomes more somber as the strike progresses, slowing the narrative pace to a crawl and making the middle section of the story feel sluggish before developing events push things along to a dramatic finish.

Sally Hawkins captures the insecurity and building confidence of Rita. She’s a good wife, mother, and worker, but the role of labor leader suits her perfectly, allowing her to come fully into her own. That buoyancy floats “Made in Dagenham” above its historical roots, allowing it to happily inhabit its own dramatic territory. Well done.

“Made in Dagenham” opens tomorrow at the Landmark Inwood and Angelika Plano.

Via respective official sites: Showtimes at Landmark Inwood | Angelika Plano.