Associated Electrical Industries (AEI) was formed in 1928 as a financial holding company for a number of leading electrical manufacturing and trading companies in the United Kingdom. The two major constituent companies were British Thomson-Houston (BTH) based at Rugby, (Mill Road Works) and Metropolitan-Vickers Electrical Company Ltd (Metrovicks) situated at Trafford Park, Manchester. However, fierce rivalry existed between the Metrovick and BTH brands resulting in internal competition and duplicated management. This was highlighted during the Second World War in 1939, when Metrovicks and BTH became the first two firms in the world to construct jet engines (independently from each other). Following the Second World War, in 1954, AEI expanded to consist of BTH, Metrovicks, Edison Swan Electric Co, Ferguson Pailin, Hotpoint Electric Appliance Co, International Refrigerator Co, Newton Victor, Sunvic Controls, Premier Electric Heaters, Siemens Bros (1955) and Birlec (1954). In 1959 AEI decided to remove the familiar brands of BTH and Metrovicks and consolidate both as AEI resulting in internal problems and a fall in sales and market value. However, AEI acquired a variety of companies from 1959 to 1967, these included Associated Insulation Products, W. T. Henley’s Telegraph Works Co (1958), and London Electric Wire Co and Smiths (1958), Submarine Cables, Hackbridge Holdings Ltd., The Lancashire Dynamo and Crypto Ltd., W.T. Avery Ltd., Henley and Schreiber. The General Electric Company bought AEI in 1967.

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.

A site on the east side of Strand Road had been intermittently used for railway work since the 1840’s. In 1898 the Electric Railway and Tramway Carriage Works Ltd (ER&TCW) took over the site. This company had strong links with Dick Kerr & Co. The building of Preston Dock in the 1880’s had involved the diversion of the river Ribble and associates of Dick Kerr & Co built the factory building which still stands on the west side of Strand Road in 1900. This site occupies the space between the road and the original river bank. The two sites became a major centre of tram building and electrical equipment manufacture. Dick Kerr & Co took over the West works in 1903 and ER&TCW became the United Electric Car Company in 1905. A major early railway contract was for the electrification of the Liverpool Southport line of the Lancashire and Yorkshire Railway in 1904. The two factories continued in close association until they merged into English Electric in 1918. Military equipment and Seaplanes were built during the First World War and the Dick Kerr & Co Work’s Ladies became a famous football team at that time. Non railway electrical work was gradually transferred to other English Electric factories in the 1920’s. Besides continuing tramway business, major orders for Japan and France helped to establish electric traction industries in those countries, the Tarbes factory continues as a main unit in the Alstom group. A complete electrification scheme was supplied for the Arthur’s Pass line in New Zealand. 1930 saw the transfer of the traction electrical work to Phoenix, Bradford and the closure of West works until the late 30’s. East works continued making buses and trams including a large order for Blackpool. Early diesel electrics became a speciality and shunter contracts with the Willans built 6K engine for the LMS and others were very successful and formed the basis of large orders after the Second World War. In the late 30’s East works open yards and some surrounding properties were built over to form a large aircraft manufacturing site and with West works produced over 3000 Handley Page bombers during the war and just post war, DeHavilland ‘Vampire’ jet fighters. After the war most traction electrical equipment manufacture (but not the offices) was moved from Bradford to East works and ‘K’, ‘RK’ and ‘V’ engine manufacture moved from Willans, Rugby to the West works which also took on diesel and electric locomotive manufacture. Aircraft manufacture continued in both works with large orders for Canberra bombers and Lightning fighters. Final assembly was at Salmesbury and Warton aerodromes. Some locomotive manufacture was subcontracted to Vulcan from the late forties. Notable orders included large Electric locomotives for Spain and the ‘5E’ for South Africa. This locomotive was the basis of subsequent large orders for ‘5E1’ and ‘6E’ equipments produced by or in conjunction with AEI and GEC Traction. The prototype ‘Deltic’ was produced before the takeover of Vulcan and Robert Stephensons in 1955, when all locomotive production was quickly moved to those sites. Most of the diesel engines for the large number of locomotives supplied under the British Rail modernisation plan were made in West works. Aircraft production continued in both works until the formation of the British Aircraft Corporation in the mid-sixties. East works was transferred to BAC and diesel engines moved to Vulcan. The full range of traction equipment manufacture then took over West works and the offices moved in from Bradford in 1967. BAC closed East works in the early nineties and the factory was demolished. Four years after the merger with GEC in 1968 the former English Electric and AEI traction offices were reorganised with commercial and control gear at Trafford Park and machines at Preston. Production locations remained unaltered until the closure of Attercliffe, Sheffield in 1985. Semi-conductor technology gradually changed the product range in the 1980’s with GTO’s and IGBT’s enabling ac induction motors to take over from dc in the 90’s. Over 5000 EE507 dc motors were made for BR Southern region over a period of nearly 50 years. After the merger with Alsthom in 1989 the Trafford Park operation was gradually closed down and all offices and production were moved to Preston in the mid-nineties. Some buildings were demolished and others refurbished. Major orders for ac motor equipments included BR classes 465 and 365, ‘Eurostar’ motors and ‘common’ blocks, Korea, London Underground ‘Jubilee’ and ‘Northern’ lines and Virgin ’Pendolino’ and ‘Voyager’ trains. Most of the motors for these last two were made at Ornans, France after the closure of new motor manufacture in 1999. After 2003 only a small design and drawing facility remained, concentrating on repairs and modifications to existing rolling stock The site remains open as part of Alstom Transport’s Train Life Service business for the manufacture, repair and overhaul of traction control equipment and rotating machines, and as a spare parts distribution centre. BAE systems have occupied some offices on the site since 2006 as tenants of Alstom. Today, the factory is still operating on a reduced scale, only employing about 200.

In 1900 the British Westinghouse Electrical & Manufacturing Co Ltd bought land in Trafford Park and built a factory which went into production in 1902 for the manufacture of mechanical and electrical equipment for the generation, transmission and use of electricity. In 1919, Trafford Park Works became owned by British Westinghouse’s successor, Metropolitan-Vickers Electrical Company (MV). The main shops, in common with factory construction throughout Trafford Park, were single floor type, with bays 1,000 feet in length, and had direct railway communication with the docks and trunk systems of the country. The main office block was a copy of the Westinghouse building in Pittsburgh, USA and the factory was to the American design and used imported steelwork for construction. Products manufactured at the Works included gas engines, stationary steam engines, electric generators, transformers, switchgear, meters, motors, control gear, and arc lamps. During the First World War, British Westinghouse built some small petrol-electric locomotives for the War Department Light Railways. In 1928 the Works were taken over by Associated Electrical Industries (AEI), which merged Metropolitan-Vickers and British Thomson-Houston, though these two companies continued their own trading names. Traction design and manufacture was always a minority of the workload at Trafford Park with the largest operations generally turbine manufacture. Very few vehicles were built there, and traction machines (i.e. motors, inductors and generators) were largely built in other places – notably at Sheffield or Rugby. Trafford Park traction manufacture was largely that of assembling control gear – contactors, switches, drivers’ controllers, camshaft controllers, relays etc. and building these into frames or equipment boxes for installation in vehicles made elsewhere. An important part of the Trafford Park Works site was the general switchgear operation, mainly for generation or distribution installations. The on-site Switchgear Testing Company was a “testing house” for these products and contributed to testing and development of traction circuit breakers and switchgear. During the Second World War MV acting for the Ministry of Aircraft Production produced more than a thousand Lancaster Bombers in the adjacent Mosley Road building. The company also manufactured war munitions and in the laboratories developed what became known as Radar. In 1959 the newly formed AEI Traction Division established its headquarters at Trafford Park, with a product range that included electric and diesel-electric locomotives; electrical equipment for tram-cars, trolley buses and trolley mining locomotives and traction motors. AEI was taken over by the General Electric Company (GEC) in 1967 whose Witton Works closed in 1969, with the design office and traction manufacture transferred to Trafford Park, as a result of the GEC reorganisation and mergers. GEC Traction Ltd took over the Works in 1972. In 1990 the former Low Voltage Switchgear site at Trafford Park (West Works) was renovated to be the new manufacturing facility for GEC Alsthom Traction, with an electronics workshop, machine shop and plating baths, and an assembly shop for switchgear, equipment cases and power modules. This building was vacated in 1998 when power modules and switchgear was moved to Tarbes in south west France. The Works housed the administrative, commercial and accounting functions, the majority of the design departments and the development section with its associated workshops and laboratories. The manufacturing area was devoted primarily to the production of components of traction control and railway signalling equipment. In 1993, as part of the rationalisation of the equipment group, it was announced that the headquarters of GEC Alsthom Traction would move to Preston, leaving only Power Module design and manufacture at Manchester, with the eventual closing of all activities at Trafford Park in 1998. The iconic original Westinghouse building was demolished and the site is now (2015) largely devoted to container handling and logistics operations.

GEC Traction (GECT) was formed in 1972 as part of the GEC Power Engineering Group following earlier amalgamations of the traction divisions of the General Electric Company (GEC), the English Electric Company (EE) and Associated Electrical Industries (AEI). A wholly owned subsidiary company of GEC, the company had offices and works, located at Trafford Park in Manchester, at Strand Road in Preston, and at Attercliffe Common, Sheffield. The headquarters of GEC Traction was Trafford Park, Manchester (previously the headquarters of English Electric-AEI Traction) with design of rotating machines at Preston and Sheffield, and manufacturing activities for control equipment at Manchester and Preston. GEC Traction designed and manufactured a full range of traction machines and control equipment for electric vehicles, including electric locomotives and multiple unit trains for main-line and mass-transit railway systems (dc up to 3,000 volts, and ac up to 50,000 volts), diesel-electric locomotives and trains, mining and industrial locomotives, tramcars and trolleybuses. GEC Traction was the leading supplier of traction equipment in the UK and had a wide market around the world, particularly in South Africa, Australasia, Hong Kong, South Korea, South America and Pakistan. In 1979 the Industrial Locomotive Division of the former English Electric which was based at Vulcan Works, Newton-le-Willows was merged into GEC Traction, which later became a separate company, GEC Industrial Locomotives Ltd. During the late 1980s and 1990s the firm underwent major rationalisation, involving closure of several sites including Attercliffe Common in Sheffield in 1985 and the company’s headquarters at Trafford Park in Manchester in 1998. The company name GEC Traction endured until a merger with the French Alsthom group in 1989, which created GEC Alsthom Traction, which was still a branch of the main company GEC Alsthom.

Metropolitan-Vickers Electrical Company Ltd (Metrovicks) built an armament factory on Attercliffe Common in Sheffield, a 9-acre site for the manufacture of traction motors in 1921. In 1923 it was made into a self-contained traction motor factory with its own engineering department and the manufacture of complete locomotives and electric delivery vehicles. Metrovicks merged with British Thomson-Houston Co Ltd (BTH) in 1928 to form the holding company Associated Electrical Industries (AEI) still trading under each individual company’s name. In 1931, Metrovicks bought the whole Attercliffe Common Works apart from the stamp shop which made 4 1/2 acres of single-storey building available for traction work. During the Second World War the Works suffered bomb damage and became the major supplier of dc generator/ high frequency alternator sets for aircraft and a ‘shadow’ factory was set up at Bamford. Together, 140000 sets were produced with military work continued at the factory up to the 1970’s. In 1956 Attercliffe Works became the feeder department for the new AEI factory on Greenland Road also located in Sheffield for the manufacture of smaller type of machines, traction gears. AEI created a subsidiary called AEI Traction Ltd in 1959, which took over the Attercliffe Common works to manufacture traction motors, generators, gears and other machines such as motor-generator sets used for converting the high traction voltage to a safer voltage suitable for train lighting, heating, battery-charging and for the control equipment on locomotives and suburban electric trains. The General Electric Company Ltd (GEC) took over AEI in 1967 and Attercliffe Works became owned by a subsidiary of GEC, GEC Traction Ltd who designed and manufactured a full range of traction machines and control equipment for electric vehicles. All British Railways a/c electric loco motors and motor coach d/c motor orders for Hong Kong and Korea up to the mid-seventies were built at the Works. The Attercliffe Common works closed in 1985 when GEC and the French Alsthom group merged in 1989, and the design and manufacture of motors and inductors moved to GEC Preston works and gears moved to GEC Rugby works.