Actually, Tale of Two Cities is written by Charles Dickens, and it's hardly a ringing endorsement of Madame Defarge's beliefs. It's clear that she's the villainess of the piece. And since Dickens is all about virtue, she does get killed off in the end.

We've had one other character mention Dickens: Neville. His gran was reading A Christmas Carol, right? I wonder if Dickens is just such a famous English writer that wizards have to co-opt him or they read him anyway. He's too influential and famous--and too much a part of British culture--to be simply ignored.