Jean-Claude of Lyon is a person not actually encountered in the game, but mentioned by Florentine in one of his Journal entries, dated October 18th 1673. His words may be vague, but Jean-Claude appears to be a deceased member of Florentine's Temple Order.
Although all new converts from the recent London meet are still among our number, I shudder to think what has befallen Jean-Claude of Lyon, David of Leicester and Paul of Durham. Whatever their fate it must be connected to the disappearance of the Dodger into the Tower. Without guidance and the correct medicine, the Servitor could spell trouble. I am currently collecting together the names of all the few who will be 'volunteering' to don Gate devices to track the thing down.