British filmmakers seem born to make these costume movies and make them well. The Duchess is no exception in this, though one would have liked a more modern appraisal of the subject, Georgiana Cavendish, Duchess of Devonshire.

A feminist eons before the word was invented, Georgiana established a salon devoted to the artists and politicos of her day and even campaigned for Whig party candidates despite not having the vote herself. But this movie, directed by Saul Dibb and based on a biography by Amanda Foreman, only notices these things insofar as they relate to her marital discord and an illicit affair. The movie doesn't seem to appreciate how modern she was.

Knightley captures all the wit, intelligence and high-born manners of a woman given little choice other than to pursue pleasure in a world engineered for and by men. Dibb, a sturdy but uninspired director, brings no Shekhar Kapur visual or dramatic flamboyance to the task of bringing Georgiana's life to the screen. So The Duchess will satisfy those who enjoy costume dramas but not reach much beyond that audience.

The Paramount Vantage release opened Friday in the UK, and then premiered Sunday at the Toronto International Film Festival before its Los Angeles and New York bows on September 19.

The movie begins with the 1774 nuptials of Georgiana Spencer and a temperamentally unsuitable duke. (Ralph Fiennes does manage to somewhat humanize the loutish noble). The duke perceives his marriage to have the sole purpose of producing a male heir. Years of miscarriages and daughters pass before this happens, though. Meanwhile, Georgiana finds her feet as a celebrity and fashion plate, making her husband seemingly the only man in Britain who is not in love with her.

She even introduces into the household Lady Elizabeth Foster (a bright, alluring Hayley Atwell), who becomes her husband's mistress. For her part, the duchess dallies with handsome politician Charles Gray (Dominic Cooper of Mamma Mia!), causing a near scandal from which the family manages to recover.

The melodrama is a bit bloodless, though, figuratively and literally. This is a not-uninteresting chapter during an exciting time in British and European politics – neither the American nor French revolutions get mentioned – but writers Dibbs, Jeffrey Hatcher and Anders Thomas Jensen find no way to connect us with these distant personages. Probably the most surprising thing to a modern audience is how aristocrats engage in the most intimate and embarrassing conduct in full view of servants who are treated as little more than furniture.