serial no. 3447/1958
H W Sullivan Ltd DC Resistance standard 100Ω 100mA maximum. The firm founded in 1922 based in London was taken over by Cambridge Instrument Company in 1967 produced precision laboratory equipment such as resistors, shunts, galvanometers, capacitors etc. until 2002 when it was incorporated into Megger Limited.
This is one of several instruments which I have been given by Ian Griffiths.