Cloth Seal, Unknown Continental, Eagle, Privy Mark, Aachen?

Cloth Seal, Continental, Eagle, Privy Mark, Aachen?, Image & Found by Chris Biz Howard.
Found in Croft near Skegness, 17mm.

Privy mark incorporating S R // eagle displayed facing left

The double-rivet and overall design suggests a Continental seal. The eagle is similar to those found on Aachen seals.