Another? - SORRY.

 Two/three reasons.
1. I've NO doubt it came with me from "Home".
2. I hadn't a clue I had a coin that age; or ANYTHING else for that matter.
3. I'm contemplating "a well known Auction site" I'm practicing to get a decent couple of shot .
       Times must have been relatively laid-back then?  Putting the date on - THEN - I checked.  Despite calling it "Gun-Money"; which, knowing "Bug-Roll" about, except its name, I looked up:-
"Gun money was an issue of coins made by the forces of James ll during the Williamite War in Ireland (I'll look THAT up later) between 1689 and 1691.  They were minted in Base Metal (copper, brass or pewter), and were designed to be redeemed for silver coins following a victory by James II and consequently bore the date in months to allow a gradual replacement.  As James lost the war, that replacement never took place, although the coins were allowed to circulate at much reduced values before the copper coinage was resumed.  They were mostly withdrawn from circulation in the early 18th century."