I have to somewhat disagree with others, shame its so worn which isn't helping an easier ID.
I think this worthy of much more study, I'm not convinced its a Regal Geo I Half Penny for the following reasons:
The position of the 'V' on the obverse seems a little off, & the position of the 'N' on the reverse is not close enough to Britannia's head.
Finally the strange clipping to the edge is odd.
If its a contemporary counterfeit of Geo I it would be an extremely rare find, I can't remember seeing any.
My guess is it's a cast counterfeit. I've never seen a legit Geo struck-off center so badly, but that's just my guess. I defer the to real experts here.
The counterfeits are often more interesting (and valuable) than the real KGs.