I purchased this one from my friend and EAC dealer described as follows: "Uniface lead cliche of the obverse a (c. 1697) Great Britain William III medal by Boskam. Doesn't get too much more obscure than this. Pretty cool thing though. "25" inked on the back - probably a museum inventory number". Any and all help with researching this one appreciated- not sure where to even start! Best, Jack.
I would like to think it was a multiple test strike piece. The bubbles on the reverse remind me of indirect die transfer.