General Electric Company in the context of Hirst Research Centre

The cavity magnetron is a high-power vacuum tube used in early radar systems and subsequently in microwave ovens and in linear particle accelerators. A cavity magnetron generates microwaves using the interaction of a stream of electrons with a magnetic field, while moving past a series of cavity resonators, which are small, open cavities in a metal block. Electrons pass by the cavities and cause microwaves to oscillate within, similar to the functioning of a whistle producing a tone when excited by an air stream blown past its opening. The resonant frequency of the arrangement is determined by the cavities' physical dimensions. Unlike other vacuum tubes, such as a klystron or a traveling-wave tube (TWT), the magnetron cannot function as an amplifier for increasing the intensity of an applied microwave signal; the magnetron serves solely as an electronic oscillator generating a microwave signal from direct-current electricity supplied to the vacuum tube.

The use of magnetic fields as a means to control the flow of an electric current was spurred by the invention of the Audion by Lee de Forest in 1906. Albert Hull of General Electric Research Laboratory, USA, began development of magnetrons to avoid de Forest's patents, but these were never completely successful. Other experimenters picked up on Hull's work and a key advance, the use of two cathodes, was introduced by Habann in Germany in 1924. Further research was limited until Okabe's 1929 Japanese paper noting the production of centimeter-wavelength signals, which led to worldwide interest. The development of magnetrons with multiple cathodes was proposed by A. L. Samuel of Bell Telephone Laboratories in 1934, leading to designs by Postumus in 1934 and Hans Hollmann in 1935. Production was taken up by Philips, General Electric Company (GEC), Telefunken and others, limited to perhaps 10 W output. By this time the klystron was producing more power and the magnetron was not widely used, although a 300 W device was built by Aleksereff and Malearoff in the USSR in 1936 (published in 1940).

The British Broadcasting Company Limited (BBC) was the commercial forerunner of the public British Broadcasting Corporation and formed on 18 October 1922 by British and American electrical companies doing business in the United Kingdom. Licensed by the UK's General Post Office, its original office was located on the second floor of Magnet House, a GEC building in London, and consisted of a room and a small antechamber.

On 14 December 1922, John Reith was hired to become the managing director of the company at that address. The company later moved its offices to the premises of the Marconi Company. The BBC as a commercial broadcasting company did not sell air time but it did carry a number of sponsored programmes paid for by British newspapers. On 31 December 1926, the company was dissolved and its assets were transferred to the non-commercial and crown-chartered British Broadcasting Corporation (BBC).

British Aerospace plc (BAe) was a British aircraft, munitions and defence-systems manufacturer that was formed in 1977. Its head office was at Warwick House in the Farnborough Aerospace Centre in Farnborough, Hampshire. It purchased Marconi Electronic Systems, the defence electronics and naval shipbuilding subsidiary of the General Electric Company, in 1999 to form BAE Systems.