Keira Knightley will play the 18th century aristocrat Georgiana, duchess of Devonshire, in Saul Dibb's The Duchess, co-financed by Pathe and BBC Films.

According to Variety, the film which is set to shoot in October, is adapted from Amanda Foreman's best-selling biography of the controversial blueblood, who has been described as the Princess Diana of her time.

An ancestor of Princess Di, she lived an extravagant, profligate and promiscuous life of political and romantic intrigue, becoming an important powerbroker amid Blighty's ruling elite but also running up catastrophic gambling debts. She was alternately feted and reviled, and widely caricatured by the popular press.