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.

The British Thomson-Houston Co. Ltd., (BTH) was created as a subsidiary of the General Electric Company, USA in 1896 to exploit the sale of products in the United Kingdom. BTH was a reconstruction of an existing firm, Laing, Wharton and Down (1886). The BTH manufacturing works were based at Rugby, Warwickshire and the company’s products included induction motors, alternators, switchgear, turbo-generators and turbines, as well as a large number of rotary converters and motor converters, primarily for chemical plants. During the First World War, BTH’s most significant contribution was the development of marine apparatus for the naval service. The 1920s saw a period of vast expansion for the company with new extensions built at many of its factories such as Willesden, Birmingham, Chesterfield and Lutterworth. BTH amalgamated with Metropolitan-Vickers Electrical Company Ltd to form Associated Electrical Industries (AEI) in 1928 although both companies retained their separate identities and continued to compete for the same contracts. BTH developed manufactured electric torpedoes and electrical components for aircraft engines, munitions, etc., during the Second World War and in 1935 independently of each other, BTH and Metropolitan-Vickers were the first two companies in the world to construct jet engines.

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.

In 1918, two prominent firms R Hornsby & Sons Ltd of Grantham (1828) and Ruston, Proctor & Co Ltd of Lincoln (1889) merged to form Ruston & Hornsby Ltd. The company made a wide range of agricultural machinery and steam, oil and gas engines. The company diversified into excavating machines, cranes, and steam locomotives, but still had substantial agricultural engineering interests in 1918. Ruston largely moved out of the agricultural machinery market in 1919, when it transferred its agricultural interests to have a controlling interest in Ransomes, Sims & Jeffries Ltd. However, it still produced agricultural machinery at its Grantham works and attempted post-war diversification in the form of the motor car, furniture, and petrol-driven tractors. In 1940, Ruston & Hornsby purchased Davey Paxman & Co (Colchester) to form the Ruston – Paxman Group. In 1962 Ruston & Hornsby purchased the Birmingham firm of Alfred Wiseman & Co Ltd., gear specialists and maker of industrial locomotive and marine gear boxes. Some of the Wiseman design and production was transferred to R&H’s Grantham factory. However the Grantham factory was closed shortly afterwards, in 1963. In November 1966, the English Electric Co Ltd acquired Ruston & Hornsby Ltd which formed part of English Electric Diesels Ltd in January 1968 which headed the production of Dorman, Kelvin, Ruston, Paxman, Napier and English Electric diesels.

The British Railways Board was an independent statutory corporation responsible for running the British railway network from 1963. It was established by the Transport Act 1962, which abolished the British Transport Commission and divided its undertakings between five newly-created bodies: the British Railways Board, the British Waterways Board, the British Transport Docks Board, the London Transport Board, and a Transport Holding Company. The British Railways Board was responsible for running the railway network, as well as managing government-owned railway hotels. Members of the British Railways Board were also appointed by the Minister for Transport. The first Chair of the British Railways Board was Dr Richard Beeching. The British Railways Board operated through regional boards, which were responsible for regional sections of the railway network. These regions were Southern, Western, London Midland, London and North Eastern, Eastern, and Scottish. Members of these regional boards were appointed by the British Railways Board, in consultation with the Minister for Transport. The British Railways Board also operated a series of committees to manage every aspect of railway control, including committees for finance, technical, works and property. These committees were frequently reorganised throughout the life of the British Railways Board, under both different Chairs of the Board and different governments. Several changes occurred during the 1960s. The Board had two new Chairs; Stanley Raymond, who replaced Richard Beeching in 1965, and his successor Henry Johnson, who became Chair in 1967. In 1968, the Transport Act transferred the control of the Sundries and Freightliner divisions from the British Railways Board to National Carriers Ltd and Freightliners Ltd. The Board retained a forty-nine per cent stake in Freightliners Ltd. During the 1970s, the British Railways Board created several subsidiary companies which were to manage some of its undertakings. These included British Transport Hotels Ltd, British Rail Engineering Ltd, and British Rail Hovercraft Ltd. Many of these subsidiary companies were sold under the Conservative governments of the 1980s. There were also two new Chairs during this time. Richard Marsh replaced Henry Johnson in 1971, and Peter Parker became chair in 1976. The privatisation of the British rail network during the 1990s radically changed the role of the British Railways Board. The Transport Act 1993 established Railtrack, a publicly-owned company. The Act transferred the ownership of track and railway infrastructure from the British Railways Board to Railtrack, in addition to the control of signals. Railtrack also replaced the British Railways Board as the body responsible for track investment and maintenance. The British Railways Board remained in existence after these changes, but only performed residual functions relating to pensions, liabilities, and non-operational railway land. The Board also continued to operate the British Transport Police service. The British Railways Board was abolished by the Transport Act 2000, which transferred the remaining functions of the Board to the newly-created Strategic Rail Authority.

In 1918 Polish State Railways (Polish name: Polskie Koleje Państwowe or PKP) was formed following the First World War after Poland gained independence and took over 2,627 miles of railway lines in the territory formerly under Prussian rule, 2,707 miles from the former Austrian territory and 4,575 miles from the Russians. In 1922 the entire railway network in Poland was divided into 9 districts: Warsaw, Radom, Vilnius, Kraków, Lviv, Stanyslaviv, Katowice, Poznań and Gdańsk. During the interwar period from 1931 to 1939 the construction of the Warsaw Main Railway Station was completed. PKP electrified more than 6,214 miles (10,000 km) of lines from 1936 to 1987. In 1939 PKP was divided into eight regions; Warsaw, Torun, Poznan, Katowice, Cracow, Radom, Lwow and Wilno, with the headquarters of PKP located in Warsaw. During the Second World War the railway was subjected to widespread bombing WW2 as it was a crucial part of the German war effort and in 1945 PKP began rebuilding the railway under Soviet occupation. Repairs were performed by the main workshops in Brest, Bydgoszcz, Lviv, Łapy, Nowy Sącz, Ostrów Wielkopolski, Piotrowice Śląskie, Poznań, Radom, Pruszków, Stanyslaviv, Stryi, Tarnów, Tczew, Warsaw-Praga and Eastern Warsaw. The 139 mile route built in 1971 to 1977 between Silesia – Zawiercie – Włoszczowa – Idzikowice – Grodzisk Mazowiecki – Warsaw, known as the Central Mainline (CMK), was the largest investment of Polish State Railways after the war. After 1990, infrastructural investments were abandoned, with the exception of replacement work. The Polish railway network shortened from 14,292 miles to 11,806 miles of which 7,418 miles were electrified. From 1991 the number of passengers using PKP decreased with the closure of some secondary lines and narrow gauge sections. The Polish State Railways Joint Stock Company (Polish name: Polskie Koleje Państwowe Spółka Akcyjna (PKP S.A.) was established on 1 January 2001 as a result of this commercialisation of the Polish State Railways state enterprise.