The VS110 is a cold cathode voltage stabiliser. VS111 is the RAF designation and AW3 is the UK Army designation. Both types were renamed CV1110.
The striking voltage is 180 volts, and the stabilised working voltage is 120 Volts. For currents of between 6 - 75 mA the voltage is maintained to five volts of the target value of 120 Volts but can vary up to 10 Volts. The VS110A has a maximum voltage variation of five Volts.
Such valves would be used to achieve stable voltages for sensitive circuits such as oscillators. Also such a tube run at constant current would form a reference voltage for a valve voltage regulator. Oscilloscopes and radar displays would be fed from fully stabilised supplies.
The classic envelope is 40 mm in diameter and, excluding the B4 base pins, is 90 mm tall.