Metropolitan-Vickers Electrical Co Ltd was the new trading name given to British Westinghouse Electric and Manufacturing Co on 8 September 1919. The predecessor company had sold its controlling share to the Metropolitan Carriage Wagon Co in 1916 in order to gain membership of the Federation of British Industries. In 1919, Vickers acquired the Metropolitan Carriage Wagon Co, along with its controlling share in British Westinghouse, prompting the change in name to Metropolitan-Vickers Electrical Co Ltd. The American owned British Westinghouse had established its English operations at Trafford Park in 1899, and Metropolitan-Vickers Electrical Co Ltd continued on the same site from 8 September 1919. The company was initially known for its electricity generators, later diversifying into the manufacture of steam turbines, switchgear, transformers, electronics and railway traction equipment. The passing of the Electricity (Supply) Act in 1926 provided a boost to the company’s post-war fortunes, with the creation of the National Grid generating demand for the company's products. In 1928, Metropolitan-Vickers Electrical Co Ltd merged with its rival British Thomson Houston Co Ltd, retaining both names for trading purposes. The following year, on 4 January 1929, Associated Electrical Industries Ltd (AEI) acquired Metropolitan-Vickers Electrical Co Ltd and the British Thomson Houston Co Ltd. Again, both trading names were retained, and a fierce rivalry was established between the firms which the parent company was unable to control. In 1931, Sir Felix Pole joined Metropolitan-Vickers Electrical Co Ltd as its new chairman. He oversaw a period of expansion for the company leading into the Second World War. In 1939, seeking a more concise name for the company, the Board of Directors decided upon Metrovicks, which became interchangeable with the official company name of Metropolitan-Vickers Electrical Co Ltd. Under Sir Felix Pole's chairmanship, Metropolitan-Vickers developed new products for the aviation industry and during the war was one of the sites where Lancaster bombers were built. In 1941, the company developed the first British axial-flow jet engine, the Metrovick F.2. Following the Second World War, the company appointed Oliver Lyttelton as chairman, with the aim of increasing the efficiency and productivity of AEI. Despite his success in achieving this aim, Lyttelton was unable to resolve the commercial rivalry between Metropolitan-Vickers Electrical Co Ltd and the British Thomson Houston Co Ltd. During his second period as chairman, from 1954-1963, Lyttelton, now Lord Chandos, oversaw the development by Metropolitan-Vickers Electrical Co Ltd of the first commercial transistor computer, the Metrovick 950. Chandos also resolved to extinguish the competition and internal divisions between Metropolitan-Vickers Electrical Co Ltd and the British Thomson Houston Co Ltd, and both company names ceased to be used from 1 January 1960, with all subsidiaries going on to trade under the name of Associated Electrical Industries Ltd.

Ferranti International plc was an electrical engineering company originally established in 1883 as S Z de Ferranti. Sebastian Ziani de Ferranti had previously worked for Siemens Brothers in London before starting his first company, Ferranti, Thompson and Ince Ltd, in 1882 to manufacture alternators. When this company was wound up in 1883, de Ferranti bought back his patents in his alternator design and set up S Z de Ferranti with C P Sparks the same year. The business became a limited liability company in 1889, changing name to S Z de Ferranti Ltd. In 1896, the company moved from London to new premises in Hollinwood, Oldham, where land and labour were cheaper. In 1901, a new company name, Ferranti Ltd, was registered. Ferranti Ltd acquired the undertakings and assets of S Z de Ferranti Ltd the same year. The company ran into financial difficulties in 1903, largely through the investment in developing steam engines and dynamos. At the instigation of the debenture stockholders the company went into voluntary receivership. In 1905, the company was relaunched under a scheme of reconstruction, with production limited to the manufacture of switch gear, transformers and instruments. De Ferranti himself took a less active role in the running of the reconstituted company. Ferranti Ltd expanded its output in 1912 from electricity generating and distribution equipment to include electrical domestic appliances, establishing the Domestic Appliance Department. Expansion overseas began in 1913 when the Ferranti Electric Company of Canada was created as a separate business to the main company. By 1914, Ferranti Ltd was spread over several sites. It suspended normal production during the First World War and concentrated on the manufacture of shells. This was the first of Ferranti’s government defence contracts. The 1920s saw a resumption of manufacturing of civilian products. In 1923, production of audio frequency transformers signalled Ferranti Ltd’s move into electronics. In 1926, the company resumed manufacturing domestic appliances, beginning with electric fires, and began trading in the United States as Ferranti Electric Inc, New York. 1927 saw the re-establishment of the Domestic Appliance Department. In 1929, Ferranti Ltd began producing commercial radio receivers and in 1935 established its Moston radio factory, to which the Domestic Appliance Department moved in 1937. Shortly afterwards, television manufacturing started at the Moston site. Sebastian Ziani de Ferranti died in 1930, and his son Vincent de Ferranti became company chairman in his place. During the 1930s, the company became closely associated with devices that would feature strongly in the Second World War, including thermionic valves (vacuum tubes) used in radios and radar, avionics and naval instruments. During the Second World War, Ferranti Ltd produced marine radar equipment, gyro gun sights for fighters and one of the world’s first IFF (Identification Friend or Foe) radar systems, which reduced the possibility of firing on friendly aircraft or ships. In 1943, the company opened its Edinburgh factory to manufacture gyro gun sights. The Edinburgh site would become Ferranti Ltd’s hub for the manufacture of military defence equipment. Ferranti Ltd retained its interest in the defence sector after the Second World War. From 1948, the company began to develop guided missiles, especially the Bloodhound, at the Moston factory and later at the Wythenshawe factory. While the defence and communication market expanded throughout the 1950s, domestic products became unprofitable and were dropped. The company sold its radio and television interests to E K Cole Ltd in 1957, and the Domestic Appliance Department closed the following year. Ferranti became increasingly associated with ‘high-tech’ devices, including microwave communications equipment built at Poynton, near Stockport. Ferranti Ltd moved into computing in 1949, with the establishment of the Computer Department. The department produced the first Ferranti Mark I computer, a commercial version of the ‘Baby’ computer developed by Manchester University, at the Moston factory in 1951. It was the world’s first commercially produced computer. Computer production moved to a factory in West Gorton in 1956, but the Computer Division was sold to International Computers and Tabulators Ltd (ICT) in 1963. Other sections of the company continued to develop computer technology for more specialised applications. Ferranti Ltd also invested in semiconductor research, leading to its development of the first European microprocessor, the F-100L, at its Bracknell plant. Ferranti Ltd also produced non-standard silicon chips to suit individual customers’ needs. The Hollinwood factory continued to produce generating plant, such as large transformers, establishing the Distribution Transformer Department in 1957. This department operated until 1967. By 1975 the company was in financial difficulty and the British Government bought a 50% stake in Ferranti Ltd to enable the company to continue developing its telecommunications and computerised control systems. In 1984, the company was restructured into five operating divisions: Ferranti Defence Systems, Ferranti Industrial Electronics, Ferranti Computer Systems, Ferranti Electronics, and Ferranti Instrumentation. Ferranti Ltd merged with the US based International Signals and Control Group in 1987. The company traded very briefly as Ferranti plc in May 1988, prior to its official name change to Ferranti International Signal plc. The US company had been over-valued because of fraudulent practice. This affected the operation of the newly formed company, and the Defence and Guided Weapons Divisions were sold off to competitors in the area of defence work. Following the discovery of the fraud in 1989, Ferranti International Signal plc was renamed Ferranti International plc in 1990. The fraud amounted to a loss to Ferranti of £215 million as a result of this the company began legal proceedings against the former Chairman of International Signals & Control Mr James Guerin and three other senior employees. Ferranti were successful and Mr Guerin was ordered to pay $189.9 million to the Ferranti group. A similar judgement was given against the others who were also ordered to repay $189.9 million to the group. As a consequence of the fraud Ferranti had to dispose of several of its interests in order to raise badly needed cash to reduce its debt burden. Amongst the companies sold were Ferranti Defence Systems Group to the General Electric Company. The Italian companies owned by Ferranti International plc were sold to Finmeccancia plc. Various other smaller interests, including civil computer maintenance, Dundee components and laser business, and a joint venture Thomson-CSF SA were also sold. Not all the money was recovered, and on 1 December 1993 Ferranti International plc went into receivership, with the remaining company divisions sold off.