Going along with the non-spoiler musings...
I figure Larry Talbot isn't present, since IIRC he wasn't an active part of the Game as an actual Player, just on the outskirts so to speak.
The Good Doctor I remember also wasn't a player directly, but given his occupation he'd still quite likely be graverobbing alongside the others, so I figure he was probably the voice looking for the patella, as mentioned.
The Vicar could have been around, but I don't see (or hear, hah) his voice as being all that aristocratic, and he doesn't seem as much a team player as the rest of the Openers, so I doubt he was involved in this night, though I could be wrong.
The Great Detective (I forget how he was involved, just that he was on the periphery, much like Talbot) is already lurking outside the graveyard, so he's not one of the voices apparently.
So I'm still not sure about the "aristocratic" voice, unless it's Morris. Hrm.
Or one other possibility I suppose is that the Detective has his assistant (Watson, who is a doctor), doing some collecting for him, and he's one of the voices, possibly the one asking for a patella, but I doubt it since a) I don't think Holmes was that involved in the first place to the point of collecting things, and b) it doesn't seem like Watson is "in the know"