As being 1/5 of a gill i.e. 1 fluid ounce. It is marked inside the base with X above Y in a triangle over +. This mark is.
SUPERB ANTIQUE PEWTER PINT TANKARD MUG CITY OF LONDON VERFICATION c1850
SUPERB ANTIQUE PEWTER BRASS RIMMED GILL TANKARD MUG MEASURE BY LOFTUS c1900
SUPERB ANTIQUE PEWTER BRASS RIMMED ½ GILL TANKARD MUG MEASURE BY LOFTUS, LONDON
SUPERB VINTAGE SHIPS WHEEL DUAL SCALE BAROMETER by Shortland- VINTAGE BAROMETER
2 Pewter Goblets - SKS Design - Vintage Pewter - Cup - Pewter