This is Jessica Mitford. If you don't know who she is, you should read Leslie Brody's biography, Irrepressible: The Life and Times of Jessica Mitford, which I reviewed for Bookforum.
(you have to sign in, but it's free! also bookforum is great!)
(i am seriously thinking of switching to Tumblr, you guys)
Apparently J.K. Rowling considers herself to be most influenced by Jessica Mitford. Fascinating, huh? So much so that she named her daughter after her. Pretty nice name!
If you're interested in more about the Mitfords, or the Mitford sisters, there are Jessica's letters, Unity's biography, or many many books by Nancy and Jessica. So have at it!