The new movie The Duchess with Keira Knightly is about Georgiana, the Duchess of Devonshire--the beautiful, witty socialite beloved of all of London in the 18th century (except of course by her husband). I've always been fascinated by her and that time. I'll be interested to see how Charles James Fox is portrayed.
I have no idea how well this movie is done, but it might be worth looking at, if only for the costumes!
Info at: http://www.npr.org/templates/story/story.p hp?storyId=94662956