Back in the late 18th century, while England was dealing with rebellion in its colonies and a call for greater democratization at home, Georgiana Spencer married William Cavendish, the Duke of Devonshire, and via her husband's Whig-affiliated circle of associates, she began taking an interest in politics, primarily by supporting the career of future prime minister (and lover) Charles Grey. In Saul Dibb's The Duchess—adapted by Jeffrey Hatcher from Amanda Foreman's biography Georgiana—Keira Knightley plays the duchess as a freethinking fashion plate, admired by the ladies of London for her sense of style and her insistence that there's no such thing as "freedom in moderation." But her domestic situation tests her public calls for universal liberty, as her husband—played with creepily calm menace by Ralph Fiennes—reminds her that she has no real power in their relationship. He can sleep with whomever he wants, and squelch her ambitions at any time, just by threatening to take away her children.
To some extent, The Duchess recalls Sofia Coppola's Marie Antoinette, in that it's about bed-hopping and courtly ritual during a time of revolution. Dibb isn't interested in delivering an audience-unfriendly art film, though. His Duchess is thoroughly populist and middlebrow, full of all the high wigs, thick powder, perfect diction, and straightforward dialogue that define bodice-ripping prestige pictures about silently suffering souls. Knightley's brand of muted iconoclasm has always been well-suited to just these kind of coach-and-corset movies, and as a result, the story of her character's fall from idealism to practicality becomes fairly moving. Dibb and company make too much of the parallels between Georgiana's story and that of her most famous descendent, Lady Diana Spencer, but at the same time, the "ironies of fame" material works well—not because of its specific application to the aristocracy, but for how it relates to the commoners. Lots of people dream of better lives for themselves and the citizens of the world. And lots of people stop short when they realize they need to stay home and tuck their kids into bed, so the next generation can have their own unfulfilled dreams someday.