According to the gossipy English period piece The Duchess, the Duke of Devonshire (Ralph Fiennes) had only met young Georgiana Spencer (Keira Knightley) twice before they became engaged in 1774. When her matchmaking mother (Charlotte Rampling) breaks the big news, Georgiana asks the inconvenient question, “Does he love me?” Usually such concerns aren’t part of the vetting process for the English nobility.

Instead, the bride must fulfill the two obligations of being well-bred and good for breeding. Given a rich, powerful husband and all that England has to offer, Georgiana must only provide the duke with a male heir. When she finds herself unable to fulfill that part of her job description, The Duchess becomes a juicy drama of domestic power struggles.

Director/co-writer Saul Dibb presents a lively adaptation of Amanda Foreman’s 1998 biography, which became a best-seller partly for showing how history repeated itself 200 years later. The marriage of popular, glamorous Georgiana to the emotionally remote duke anticipated the tribulations of Princess Diana, who was related to Georgiana’s brother through the Spencer line.

THE DUCHESS’ FOCUS ON PRE-FEMINIST SOCIAL PREDICAMENTS MAKE IT MORE INTELLIGENT AND CLASSY THAN THE USUAL ROYAL BODICE RIPPER.

The Duchess’ focus on pre-feminist social predicaments make it more intelligent and classy than the usual royal bodice ripper. The film’s themes of childbirth and the female influence on the political process prove particularly timely for its American release and find echoes not just in the House of Windsor, but also in Wasilla, Alaska.

Georgiana becomes the toast of England’s high society following her wedding, and wins the nickname the “Empress of Fashion” for her dress designs. Called “G” by her politically influential friends, she flourishes in the scrutiny of crowds while being tailed by cartoonists with sketchpads, as opposed to paparazzi with flashbulbs. The Duchess offers a persuasive portrait of 18th-century fame and culture without resorting to the pop-culture anachronisms of Sofia Coppola’s Marie Antoinette.

The duke speaks to his dogs more than his wife. Nevertheless, when Georgiana delivers two daughters and two stillborn sons, he seethes over his lack of heir and how it reflects on him. Georgiana turns a blind eye to his mistresses and even raises the daughter of a previous assignation as her own. She finds a confidante in plain-speaking Lady Bess Foster (Hayley Atwell of this year’s Brideshead Revisited), whose ex-husband refuses to let her see her children.

Georgiana casually manipulates the duke into inviting Bess to be their houseguest. Bess proves worldlier than she initially lets on, teaching her friend that sex can be about more than reproduction in a near-Sapphic clench. Bess’ “unclaimed” status and her proven ability to bear sons make her more of a potential rival than Georgiana can imagine. Spurned, Georgiana returns the affections of a childhood sweetheart (Dominic Cooper), but the duke enforces a double standard for infidelity, and Georgiana’s own mother backs him up.

Knightley tends to present her role’s feelings in bright primary colors rather than more complex, subtle hues, even as she’s graduated from popcorn films such as Pirates of the Caribbean to more self-consciously prestigious fare. She doesn’t seem quite physically or intellectually mature enough to be a leading light of England’s most influential salons, but she captures the young Georgiana’s youthful spark and wounded feelings well enough.

Fiennes gives consistency and gravitas to a role that could be an upper-class blank. Closed off and capable of callous brutality, Fiennes’ duke still comes across as an unpredictable, three-dimensional figure.

The Duchess doesn’t match production company Merchant Ivory’s adaptations of E.M. Forster, but director Saul Dibb nevertheless fosters intimacy with his aristocratic characters.

At a time of inherited titles, an infant son proves to be an even more valuable political prop than the various candidates’ children in the 2008 election. In The Duchess, Georgiana and Bess make wrenching, tear-jerking decisions based on whether or not they can remain with their children, endorsing the parental bond over one’s romantic passion or public station.

THE DUCHESS (3) Directed by Saul Dibb. • Starring Keira Knightley and Ralph Fiennes. • PG-13, 110 min. • At Osio Cinemas.