Information: - A diesel multiple unit or DMU is a multiple-unit train powered by on-board diesel engines. A DMU requires no separate locomotive, as the engines are incorporated into one or more of the carriages. They may also be referred to as a railcar or railmotor, depending on country. Diesel-powered units may be further classified by their transmission type: diesel-electric (DEMU), diesel-mechanical (DMMU) or diesel-hydraulic (DHMU). - The railway system in Great Britain is the oldest in the world: the world's first locomotive-hauled public railway opened in 1825. Most of the railway track is managed by Network Rail, which in 2015 had a network of of standard-gauge lines, of which were electrified. These lines range from single to quadruple track or more. In addition, some cities have separate rail-based mass transit systems (including the extensive and historic London Underground). There are also several private railways (some of them narrow-gauge), which are primarily short tourist lines. The British railway network is connected with that of continental Europe by an undersea rail link, the Channel Tunnel, opened in 1994. - The Class 123 was a design of Diesel Multiple Unit built for British Rail in 1963 . They were built by British Rail at Swindon Works , and designed like all Swindon units as inter-city sets . Ten of the four - car sets were built and introduced in 1963 . The units bear a visible similarity to the British Rail Class 309 ; however , there is no ' relation ' here as the two types were built by different manufacturers for different markets . Swindon - built DMUs , including the Class 123 and 124 , had a structure and internal construction with much more in common with BR coaching stock ( British Rail Mark 1 ) than they do with many DMU classes . The carriage underframes were longer ( Mk1 standard main - line 63 ft 6 in ( 19.35 m ) frames , vs the 57 ft 0 in ( 17.37 m ) frames common to most 1st generation DMUs ) and the units were provided with Mk1 - style '' Pullman '' gangways instead of the '' British Standard Gangways '' fitted to most contemporary DMUs of the period . It was also unusual for a first - generation DMU to sport a front end gangway . None of these units survive today . - Swindon railway works were built by the Great Western Railway in 1841 in Swindon, Wiltshire, United Kingdom. - The British Railways Board (BRB) was a nationalised industry in the United Kingdom that operated from 1963 to 2001. Until 1997 it was responsible for most railway services in Great Britain, trading under the brand name British Railways and, from 1965, British Rail. It did not operate railways in Northern Ireland, where railways were the responsibility of the Government of Northern Ireland. - Total Operations Processing System, or TOPS, is a computer system for managing the locomotives and rolling stock (railroad cars) owned by and/or operated on a rail system. It was originally developed by the American-based Southern Pacific Railroad and was widely sold; it is best known in Britain for its use by British Rail (BR) and its successors. - The British Transport Commission (BTC) was created by Clement Attlee's post-war Labour government as a part of its nationalisation programme, to oversee railways, canals and road freight transport in Great Britain (Northern Ireland had the separate Ulster Transport Authority). Its general duty under the Transport Act 1947 was to provide "an efficient, adequate, economical and properly integrated system of public inland transport and port facilities within Great Britain for passengers and goods", excluding transport by air. - The British Rail Class 309 "Clacton Express" electric multiple units (EMUs) were built by British Rail (BR) York Carriage Works from 19621963. They were initially classified as Class AM9 before the introduction of TOPS. These units were the first express 25 kV alternating current (AC) units to be built by British Rail, and British Rail's first EMUs to be capable of 100mph. - A railcar, in British English and Australian English, is a self-propelled railway vehicle designed to transport passengers. The term "railcar" is usually used in reference to a train consisting of a single coach (carriage, car), with a driver's cab at one or both ends. Some railways, e.g., the Great Western Railway, used the term Railmotor. If it is able to pull a full train, it is rather called a motor coach or a motor car. - The privatisation of British Rail (BR) was the process by which ownership and operation of the railways of Great Britain passed from government control into private hands. Begun in 1994, it had been completed by 1997. - The Great Western Railway (GWR) was a British railway company that linked London with The Midlands, the south-west and west of England and most of Wales. It was founded in 1833, received its enabling Act of Parliament on 31 August 1835 and ran its first trains in 1838. It was engineered by Isambard Kingdom Brunel, who chose a broad gauge of -- later slightly widened to -- but, from 1854, a series of amalgamations saw it also operate standard-gauge trains; the last broad-gauge services were operated in 1892. The GWR was the only company to keep its identity through the Railways Act 1921, which amalgamated it with the remaining independent railways within its territory, and it was finally merged at the end of 1947 when it was nationalised and became the Western Region of British Railways. - A locomotive or engine is a rail transport vehicle that provides the motive power for a train. The word originates from the Latin "loco" "from a place", ablative of "locus", "place" + Medieval Latin "motivus", "causing motion", and is a shortened form of the term "locomotive engine", first used in the early 19th century to distinguish between mobile and stationary steam engines. - British Railways (BR), which from 1965 traded as British Rail, was the operator of most of the rail transport in Great Britain between 1948 and 1997. It was formed from the nationalisation of the "Big Four" British railway companies and lasted until the gradual privatisation of British Rail, in stages between 1994 and 1997. Originally a trading brand of the Railway Executive of the British Transport Commission, it became an independent statutory corporation in 1962: the British Railways Board. Given the paragraphs above, decide what entity has the relation 'operator' with 'western region of british railways'.
Answer:
british rail class 123