Hayley Atwell, left, and Keira Knightley in “The Duchess,’’ about Georgiana Spencer.

By BARBARA KANTROWITZ

Born to one of the richest families in England, she married into a clan that was even wealthier and more eminent. Her husband was nearly a decade older and never pretended to feel anything close to the romantic love she yearned for. Instead he took a mistress. But if he didn’t want his wife, just about everyone else did. She was a huge celebrity with a unique sense of style that was widely copied. Above all, she was devoted to her children.
Does the story line sound familiar?
Diana, Princess of Wales, was not the first member of the aristocratic Spencer family to win the heart of her country but not her husband. In 1774 her ancestor Lady Georgiana Spencer married the Duke of Devonshire, who had been considered the most eligible bachelor in England. Their sad union is the focus of “The Duchess,” which opened September 5 in England before its release in other countries.
Based on Amanda Foreman’s 1998 bestselling biography, “Georgiana: Duchess of Devonshire,” the film concentrates on only about 10 years in Georgiana’s life, starting with her arranged marriage at 17. It’s a compelling story, but period films like “The Duchess” are a hard sell to mass audiences, even when they have big names like Keira Knightley in the title role and Ralph Fiennes as her husband. With so many uncanny parallels in the two women’s lives, pushing the Diana connection is an obvious marketing tactic.
Like Diana, Georgiana, whom friends called G, was thrust into public life with little preparation through marriage to a famous man. Her every move was chronicled in the tabloids of the day. Diana took up causes like AIDS and land-mine victims; Georgiana was passionate about politics, even though women could not vote. She campaigned, raised money and recruited for the Whig Party until the day she died in 1806 at 48, Ms. Foreman said.
Both Diana and Georgiana had to contend with other women in their marriages. With Diana, it was Camilla Parker Bowles, whose relationship with Prince Charles began many years before Diana entered the picture. Lonely and dissatisfied, Georgiana unwittingly created her own menage a trois when she invited Lady Elizabeth Foster (known as Bess) to live with her as a companion. Bess became her closest friend, but before long the duke was equally entranced. He and Bess became lovers, and three years after Georgiana died, he married her. Poor Charles had to wait nearly eight years after Diana’s death to wed Camilla.
Like Diana, Georgiana also sought affection elsewhere. The love of her life was Charles Grey, a prominent Whig who was eventually elected prime minister. (Earl Grey tea is named after him.) They had an affair, and Georgiana became pregnant with his child. Her husband threatened to keep their three children away from her if she lived with Grey, so she went to France to have the child and surrendered the little girl, named Eliza Courtney, to Grey’s family.
Perhaps the most eerie parallel is that both Diana and Georgiana had the eating disorder bulimia, apparently brought on by the emotional insecurity of a loveless marriage.
Like Diana, Georgiana “literally couldn’t walk outside her house without being besieged,” Ms. Foreman said. “She absolutely struggled to find a way to be herself when everyone was trying to define her.” Politics gave her life meaning.
Ms. Foreman is less sanguine about comparing the two marriages: “It’s as Tolstoy says, every unhappy family is unhappy in its own way.”
The filmmakers say comparisons to Diana aren’t the only draw for modern audiences. The director, Saul Dibb, said he thought that women would relate to Georgiana’s struggles: “This terribly bright and talented woman is constantly fighting to try and find a kind of freedom for herself. And is constantly thwarted in the process.”