A check of all pre-1950* 32+ mm coppers listed on Numista gave exactly one** possibility -
this type (the George IV large Irish penny).
I'm not sure that's it; it could be some type that's listed on Numista but not mentioned as copper, or some type that's not on Numista at all. (Or I suppose a post-1950 type, but that's unlikely.) But it certainly looks similar.
*) a search not limited by pre-1950 is overwhelmed by modern crown-sized cupronickel
**) technically, there's another - the Monaco decime of 1838; but it's not as similar, and much less likely
Edited by january1may
02/08/2016 11:02 am