Page Turner: Marlboro lights! Camera! Action! Keira weighs in

Rare is the writer who can launch not just a surprise bestseller but a whole new genre. Nick Hornby did it with Fever Pitch and lo, the world was filled with tough-tender bulletins from the male psyche: lad-lit was born. Dava Sobel launched all those single-issue, slender volumes with one-name titles like Salt or Cod, with her bestseller Longitude, a book-length version of the wall captions at Greenwich's Royal Observatory.

While pop-hist studies of nutmegs or owls are now rather out of fashion, Amanda Foreman's epochal Georgiana still inspires authors today: there are myriad titles focusing on otherwise obscure historical women. This year alone we've seen a biography of Laetitia Pilkington, the "queen of the wits" hitherto only known to experts on the 18th century (Faber), and weighty studies of king's mistress Madame de Maintenon; Marie-Therese of France, hapless daughter to Marie-Antoinette (both Bloomsbury); and Dorothy Osborne, whose touching and assertive wooing of her lover Sir William Temple is the focus of Jane Dunn's Read My Heart (Harper Press).

But Georgiana was the original, and Foreman, who once posed naked, was the archetypal babe historian. They're all over the place these days, flicking their blonde locks and flaunting their scholarship. Now the film version, The Duchess, looks like launching Georgiana-mania all over again. Ralph Fiennes and Keira Knightley play the Duke and Duchess of Devonshire in a lavish and bumptious historical drama about a dynastic marriage gone horribly wrong. Georgiana was of course a Spencer woman, and the parallels are striking; Fiennes even delivers a version of the infamous "Whatever love means" line.

In a relentlessly pretty production, it falls to The Line of Beauty's Hayley Atwell to play the minger role of Bess, the Duke's mistress, though you can't help thinking he simply fancied a woman with a bosom. I've heard of a washboard stomach, but a washboard chest?

Let's not be mean to Knightley; for once her frail physique actually adds to the role. That Other Spencer Girl had a few problems with food too, and here Georgiana is shown toying at her dinners in distress. I've not been the hugest fan of La Knightley, but I thought she aced it as the fashion plate who couldn't find love at home. Judging from the mutter I heard as I left the preview cinema – 'Oh, isn't she annoying?' – not everyone will agree.