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of Farnham Road, Slough, Buckinghamshire. Telephone: Slough 900. Telegraphic Address: "Resistance, Slough"
1921 Leonard Satchwell and a Mr Johns, in partnership, founded the Rheostatic Company in Slough. The company manufactured variable resistors for controlling the speed of trams and trolleybuses.
1927 the company introduced the world's first commercially available thermostat, for the control of electric heaters and, soon after, a room thermostat.
Late 1920s moved to larger premises in Farnham Road, Slough.
1937 Became a public company
1937 Listed Exhibitor - British Industries Fair. Automatic Temperature Controls, including Thermostats for electric water heaters, cookers and room heaters, and Complete Controls for automatic firing apparatus and central heating. Electric Valves, Relays and Thermal Safety Devices. (Stand Nos. Cb.511 and Cb.410) 
1937 Manufacturers of automatic temperature controls. Satchwell Thermostats. Service Resistances. 
1939 The premises were destroyed by fire but were completely rebuilt in six weeks.
WWII As a result of the need for fuel economy, a compensator was developed that enabled heating systems in public buildings to be controlled automatically, depending on the temperature of the weather. The firm's resistors were also in demand for use by the Royal Navy and the Royal Air Force, especially to shield shipboard equipment from the harmful influence of nearby magnetized instruments.
1948 Patent - Improvements in rotary, electric switches.
1951 Patent - Improvements in safety switches for electrically heated appliances.
1953 the company sold its resistor business to Metal Industries and concentrated on Satchwell temperature control systems.
1962 New factories established at East Kilbride and further capacity being constructed at Maryport
1963 the Rheostatic Company was renamed Satchwell Controls; 2 divisions - one at East Kilbride, the other at Slough.
1967 the company was part of Elliott Automation, which was itself absorbed by the English Electric Company and so became part of the General Electric Company (GEC), the largest electrical manufacturer in Britain.