Very pleased with the comments on the 14 + N above. Thank you.
Not eBay. A Canadian seller. 19 Dollars Inc postage. Converts to around £11. Expected end of Nov.
It certainly is, and quite a find - well done! (The easiest identifier is the less bulgy forehead than obv. 15) The condition is smashing too! I believe this might only be the fourth known? Is it yours? An eBay find? Hats off to you!!
My only thought is... die fill has occurred, then somehow the build-up in the die has fallen off and been struck onto the coin. Maybe.
I'm not sure what else it could be.