A lonely half gallon Royal Navy copper rum measure with the GR cypher and Bloc lettering.
The correct term is Grog measure as it held rum mixed with water.
The GR cypher has a crown above and the digit 6 below, alongside the letter L over 52. The base has a vocabulary number of 53170. It has a riveted handle as is standard of British made rum measures.
Stands 14cm high.