Cambridge Instrument Co Ltd Resistance box 0 to 1.11MΩ Resistors are Constantin wire wound. I have two of these which used to belong to the late Mr R M Nightingale and was given to me by his daughter in 2013. Roy Nightingale worked at Cambridge Instruments for many years. Cambridge UK date unknown.
Cropico Type RBB5 Resistance box 0 to 111Ω 0.5% on three highest ranges and 1% and 2% on the two lowest. Resistors are Manganin wire wound. Made by Croydon precision Instrument Company. The firm which was founded in 1952 is now part of the Seaward group of companies. Dr Malcolm Dye MIEE has provided an interesting history of the firm in the early 1960s see here which includes some interesting details about the manufacture of these resistance boxes. The RBB range of decade resistors are still manufactured today. Croydon UK date unknown.
Lektrokit was a trade name of A P T Electronic Industries Ltd of Chertsey Road, BYFLEET, Surrey. Originally, in the 1950's, the firm was known as All Power Transformers Ltd. By 1978 the firm then known as Electerminations Limited was in liquidation.
