In the hype surrounding The Duchess—including the film's own marketing—much has been made of the parallels between the film's subject, Georgiana, the Duchess of Devonshire, and her real-life direct descendant, Princess Diana. The film's star (and period piece habitué), Keira Knightley, has herself dismissed the comparison, contending that Georgiana is a fascinating enough figure to render it unnecessary, a point of view that appears to be seconded by the filmmakers, who—though they easily could have—never address it in the film. It's a concept that has been pushed after the fact, based mainly on the influence both women enjoyed in fashion, and on the less-than-enjoyable three-party marital relationships they both endured.
Knightley is right; Georgiana does not need the Diana hook, and her story is very much her own. Advantageously married at 17 to the Duke of Devonshire (here played by a cold, complicated Ralph Fiennes), Georgiana became famous for her style and charisma, as well as her political bolstering of Charles Grey (Dominic Cooper)—who later became prime minister, and with whom she had an affair. Adding to the scandal is the fact that the Duke made Georgiana's best friend, Bess Foster (Hayley Atwell), his mistress, forcing Georgiana to tolerate all three of them living under one roof.
Though there's no shortage of drama at play here, there are long stretches of The Duchess that move very slowly—fortunately, it's a handsome film (and at times impressively racy), and fans of the view into 18th century England's opulent high society will pass the time amiably enough. Besides, it pays off, gradually becoming a surprisingly substantial and anguished damning of the gilded cages in which women of Georgiana's ilk were kept—used as baby machines, manipulated with threats of separation from their children, and forced to endure humiliation.