Someone is reading over Mr Denistoun's shoulder. I hate it when that happens.
Two things: firstly, it actually says that his attention is caught by something by his left elbow, but I've gone for the right, partly for compositional reasons, partly I just got it into my head it was that way.
Secondly, Denistoun takes off the crucifix that the daughter ominously gives him, so that should be on the table, probably. That I just forgot about.