Beynac castle looks a bit more "palatial" to me than Berze le Chatel.
Ian Pirie (Die another day, Gangs of New York, The Dark Knight, The Terror etc.) has been cast as "Henri". Ingwar can you remember a character named "Henri" in the book? The Henry's of France were only kings around the 16th century. The Charles' reigned during the time of the story.