I don't see what the problem is: "It was found among the papers left by Dr. Robert Clarke, of Settle, Yorkshire. Clarke was a collector of old letters of note and famous signatures."
What, a third person's word about what was found in some dead dude's personal effects 100 years after the event isn't good provenance? They're English, they wouldn't lie...would they?
I'm sticking to cards and related images; I don't need provenance on them.
