I was going to say, it looks like a very badly mangled old British penny, but then I noticed the big N or Z on it, so it's not that.
But the figure on the front looks a bit like Britannia with her shield.
Probably this is very wide of the mark.
(edit)
These all have the figure facing to the right.
http://www.ukcoinpics.co.uk/pen3.html