M-O Valve Co
of Brook Green, Hammersmith, London.
1919 Private company.
1920 Jan. Physical and Optical Societies Exhibition. Exhibited wireless telegraphy.
1927 Recorded as being a subsidiary of GEC
Continued to supply valves to Marconi.
1956 GEC purchased EMI's share in the M-O Valve company.
1958 Business had been focussed on thermionic devices for telecommunications, radar and military, and cathode ray tubes
1961 Manufacturers of electronic and thermionic valves, cathode ray tubes and devices, magnatrons, hydrogen thyratrons, klystrons, backward wave oscillators, travelling waves tubes, T.R. cells and geiger-muller counters. 1,500 employees.
1969 Formation of GEC Electronic Tubes to bring together M-O Valve Co and English Electric Valve Co, a company which would have half of UK valve production, the largest specialised valve manufacturer outside USA.