Screenwriters Jeffrey Hatcher and Anders Thomas Jensen draw from Amanda Foreman’s 1998 book “Georgiana, Duchess of Devonshire” for a period piece with easy-to-read resonances with the present-day. The press notes invoke some rather passé references by calling the title Duchess “the original ‘It Girl.’” “Like her direct descendent Princess Diana, she was ravishing, glamorous and adored by an entire country.” Nothing like a special thanks to the current Duke and Duchess of Devonshire to underscore the story’s lineage. An unusually long seventy-word disclaimer qualifies the artistic licenses taken with history. A lens on the past is literalized in recurring shots through windowpanes: eighteenth-century glass was visibly imperfect. The duchess (Keira Knightley) finds her means of expression warped by Enlightenment notions of freedom that do not trickle her way. When the perfectly horrid Duke (Ralph Fiennes) remarks on the finery preferred by her gender, his Lady replies: “It’s our way of expressing ourselves, I guess. You have so many ways of expressing yourselves. We must make do with our hats, our dresses.” The Duchess does express herself with flair on behalf of Whig politicos, lending her celebrity to the cause. Her century’s precursors to paparazzi sketch her comings and goings for the gossip pages. U.K. director and co-writer Saul Dibb’s main concern, though, is her stormy marriage, her romance with the future Prime Minister Charles Grey (Dominic Cooper), and a negotiated arrangement after her best friend, Lady Elizabeth “Bess” (Hayley Atwell), moves in as the Duke’s permanent mistress. “The Duchess” is high-minded melodrama about a privileged woman’s self-made emancipation in a royal patriarchy where she was born only to birth male heirs and wear feathered hats. With Charlotte Rampling, Simon McBurney, Aidan McArdle, John Shrapnel and Alistair Petrie. 109m. (Bill Stamets)