Laureate bust of the King left, with long hair, CAROLVS. A. CAROLO, rev  crowned harp within Garter, 34mm (MI 599/285), Struck en médaille. 
 
Good fine, perhaps a treasured pocket-piece, extremely rare.
 
Note    It is easy to see why Medallic Illustrations suggests the link to coinage, and it fits well with the regal copper issues of 1680-1684.  Whilst none of the more recent coin catalogues follow through on the idea, it should not be dismissed out of hand.  The CAROLVS. A. CAROLO legend is one associated with English regal Farthings and Halfpence, first appearing on patterns in 1665.