Lady Susan, not published in the author's lifetime - and recently 'novelised' by the film's writer. The book is bitchily great, and the film isn't quite good enough. It's clear the cast of luvvies had a lot of fun making it, especially the dressing up and the hair and the sets - Kate Beckinsale alone seems to have three different hair artists working on her. Despite this, though, she's just not mean enough - the Lady Susan in the book is really rather darker.
I note in passing that the best friend character has been turned in to an American - she isn't in the book. Haven't we grown out of that yet?
It's watchable enough though, and there are quite a few laughs, and it did persuade me to read the book (free for kindle, unlike the re-novelisation), so not a complete loss.
Watched at the Everyman Cinema in Muswell Hill, in one of the newly refitted screens - a bigger screen than previously, sofa seats with little tables on the arms for drinks and snacks. It's clear where the cinema business model is going.