The M-O Valve Company was formed in October 1919 from GEC-Osram which set up operations manufacturing valves for military communications as early as February 1917. Much research was done into transmitting valves and resulted, in the 20s, in valves such as the CAT14 which was used in the Daventry transmitters (later Droitwich) and the CAT15 which was employed in the BBCs first television transmitter at Alexandra Palace.
The CAT 15 was the prototype of the VT58, a valve which was extensively used throughout the Second World War. In 1940 a magnetron was produced which became the first efficient 10cm copper block magnetron for airborne use which was used in the famous H2S equipment and the Mk. VIII enemy interception gear.
Many other firsts are attributable to the company which claims to be the largest producer of instrumentation and radar cathode-ray tubes in Europe.