It does indeed, (not the dreaded PMD ?) the coin appears to be circular ill take some pics with my digi measure and some against a similar coin.
The UK has had a huge problem with counterfeit pounds. I have read a sizeable percentage of those in circulation were counterfeit. I wonder if this is one of those? I would not know what to look for.
It is unlikely that is counterfeit. This should give you all the info to check your coin against. https://en.numista.com/catalogue/pieces100658.html