Museums sell replica coins - sometimes made out of resin or similar. In design, very convincing, sometimes they have the initials of the manufacturers impressed into them, but small, so not that easy to spot. The Elizabeth 3d I was sold was in every way convincing, except it was twice as thick as it should be. Thanks everybody for your replies. I'm still not 100% convinced that this coin is not genuine. All the replicas that I can find on the internet, and all the comments on here, seem to suggest that the coin would either be marked 'copy' (in tiny writing) or would have 'r' for replica or perhaps manufacturers initials. I can find no such mark on this coin, although I note with interest that the replica HERE has the same 1562 date but clearly says 'copy' below the shield.