I have just finished reading The Strange Case of Dr. Jekyll and Mr. Hyde. Jekyll drank a potion that allowed him to turn into Hyde, who was an evil and murderous man. Jekyll eventually started to turn into Hyde unconsciously in his sleep. Cavendish can turn into his evil alter-ego, Hakuba, unconsciously in his sleep also. Cavendish Square is a location in the book, and I think that Oda read it and decided to name Cavendish off of this location, and then make Cavendish like Dr. Jekyll. I'm sure that this has been pointed out before though.