I finally figured that out but she wouldn't give me the key. She doesn't want anyone in William's study, no way, no how! Got the film from Robert and took a pic of the symbol on the wall but can't go to town to get it developed. Talked to Henry, the gardener, and asked him for the claim ticket to retrieve the stone w/ruby that he pawned. He doesn't know where it is and no amount of badgering will help. So I'm stuck in several places. Time to call it a night and start fresh tomorrow.
Its one of those doors that needs a thingy thing.