The Falklands Islands in my pocket

Going through my change today and found this - a 20p "Falkland Islands" coin.  

Apparently its a Romney Marsh sheep.engraved by Robert Elderton - who also created the Lady Diana Memorial Medal.  4.250 were minted of this 1987 variety - so what chance that one ended up in my pocket?

They've only been minted in two years from what I can tell - 1987 and 1999 (the later 2007 version has a new Queen's head).  They appear to sell for about £3 on eBay - which is a respectable markup.  I think I'll keep mine.