Countermark

https://rpc.ashmus.ox.ac.uk/countermark/955 
GIC 841
uncertain (possibly club?) (on silver coins)
On silver coins 

Coins with this countermark

Number Image TypeNumber CoinNumber VolumeNumber
RPC IV, 1510 (temporary) Show 3178 1 4.2
RPC IV, 2737 (temporary) Show 3179 1 4.2
RPC IV, 11780 (temporary) Show 3180 2 4.2