M A & C Seal, Image by StuE, Found by Jammy Ged.
Found in Yorkshire, 22mm. 12.3g.
One side has M.A&C in raised letters across the middle - possibly Co but the edge of the seal is reached after the C. The other side has a raised circular border with a large numeral 1 with COPT.b curved below it. The b is in Cyrillic script and probably short for brack / quality control which is fits well with copt that is a word for grade. It has been assigned to the Russian section due to the Cyrillic script but of course many other countries use it.