I still stand by the assumptions that:
a) this is a mock-up of some kind, or at least a staged piece. Such a thing needn't necessarily have been particularly good or realistic, especially considering this may have been an amateur photographer. All the props and their positions indicate this to me.
b) it's in a crypt and doesn't have a glass ceiling! (note there are no windows either). It could also be a Victorian construction made to look like a gothic crypt, but which turned out more like a pastiche of lots of different styles, thus the Eastern/Western church motifs and designs.
c) that's a lady or a dressmaker's dummy in the back corner - but I think whoever mentioned a double exposure might be right...I wonder then whether this is a deliberate double exposure, attempting to create a "spirit" photograph? Would fit with the owners of the house....
Doesn't explain why this appears to be a photo of a photo though
