[citation needed] In 1939, M-OV acquired two disused cotton mills at Shaw, Oldham where it established a shadow factory to produce valves and cathode ray tubes.
The company continued to manufacture valves at the Brook Green Works, Hammersmith, London, until 1988.
Notable products of the company included cathode ray tubes for television, starting in the 1930s.
In 1922 the company brought out valves using thoriated tungsten filaments, which needed less battery power to operate than former types.
During World War II the company developed the CV122 valve used in the proximity fuse.