Is this a copper coin? The dark spots on the reverse concern me - I would evaluate for potential environmental damage. In the American grading scale, I'd call it AU-50.
Nothing you can really do about dark spots on copper and bronze coins. Any attempt to try and "fix" it will just cause more damage. It's still a nice and original AU example of an uncommon coin.
I don't think that I can get it here in the Uk. I'll probably just leave it I getting a better example anyway since I had a brain fart.