Hi, I have ordered a catalogue of co-op tokens to help with my collection which should arrive in a day or two….. i can check for you then hopefully … finally managed to find what looks like a good catalogue of all the British co-op tokens …
there are 2 entries in the book I received today for Portsea 10/ ….. one with a milled edge and one with a plain edge …. Description is 19mm, bronze, for both.
If your dimensions and metal match up, it would be fairly certain that yours is a proper token …..