George III Coin - Gold Plated Copper?

Another donation to Oxfam in Exeter (UK). The weight and diameter seem to fall between the regular half penny and the penny. I found this:

N#72596

I realise the coin has been polished, but is this what it is?

Weight 12 g approx. Diameter 31 mm approx.

Date ends in 9.

Just a guess but I would think more likely the circulation version based on the amount of wear. Regardless, with the condition it's in I don't think you can represent it as the non-circulated one.

N#5616

thanks :-)