Built between 1957 and 1968 for use on light mixed freight trains, 228 English Electric Type 1 (later to become Class 20) locomotives were built. Affectionately known as 'Choppers', due to their distinctive engine sound, most of the class have now been retired from traffic but a few remain working, particularly with GBRf. Six locomotives were sold to Hunslet-Barclay and modified following withdrawal in 1989 for contract freight traffic and weed killing trains. Subsequently sold on to DRS, 20901 and 20905 were purchased by the Harry Needle Railroad Company and were then hired to GBRf for transporting London Underground stock between London and Derby, being painted into GBRf Europorte's Blue and Gold livery for the duration of the contract.

Locomotive D8325 was built at the English Electric Vulcan Foundry in February 1968 and initially allocated to the Polmadie engine shed. In 1973 the locomotive reived a TOPS classification number of 20225 before being renumbered 20905 in August 1989 following modifications to 20/9 specifications.

Built between 1962 and 1968, the British Rail (BR) Class 47 Co-Co Diesel-Electric locomotive was once the most numerous class of mainline diesel in Britain with 512 examples. 310 locomotives were constructed by Brush in Loughborough, and the remaining 202 at Crewe. The locomotives were used for passenger and freight operations. In 2020, 24 of the class remain operational on the national network with more in storage and an additional 31 preserved. Built in October 1964 as D1767 the locomotive was initially assigned to the Tinsley depot. Under TOPS the locomotive was initially numbered 47172.

The locomotive received the name ‘County of Hertfordshire’ in 1979 before being reclassified a class 47/4 and renumbered 47583 in November 1980. In 1981 the livery of the locomotive was updated to mark the wedding of HRH Prince Charles and Lady Diana Spencer featuring a large BR arrow uniquely lined in Red and Blue.

Entering service as the English Electric Type 3, the British Rail Class 37 diesel locomotives were built at the Vulcan Foundry in Newton-le-Willows in a Co-Co configuration, based on locomotive designs for export markets. Built to undertake both freight and passenger work across all BR sectors, these engines proved highly reliable and, after overhaul, many survived in service across the network into the 1990s. British Rail first placed an order for forty-two Class 37 locomotives in January 1959, the first of which was delivered in November 1960, entering service on 2 December with the last of this original batch complete by mid-1962, by which time subsequent orders had been placed. The last of the 309 locomotives built was delivered to the Western Region on 9 November 1965, originally numbered in the range D6700-D6999 and D6600-D6608. Many Class 37 Locomotives were refurbished in the 1980s, extending their life.

As a result, the Class 37 remains in service to this day as one of the longest serving classes on British railways. Second-hand locomotives have been exported to railways in France and Spain whilst in the UK many locomotives no longer required to work have been preserved. Locomotive D6817 was built in March 1963 and renumbered to 37117 under the TOPS system in 1974. In 1988 the locomotive was refurbished and renumbered becoming Class 37/5 37521. After privatisation of British Rail the locomotive passed to EWS ownership and remined in service until 2007. After a few years in storage the locomotive was purchased by the Harry Needle Railroad Company before being sold again in 2013 to Direct Rail Services. The locomotive was later purchased by a private owner before being purchased by Colas Rail Freight in 2018.

Entering service as the English Electric Type 3, the British Rail Class 37 diesel locomotives were built at the Vulcan Foundry in Newton-le-Willows in a Co-Co configuration, based on locomotive designs for export markets. Built to undertake both freight and passenger work across all BR sectors, these engines proved highly reliable and, after overhaul, many survived in service across the network into the 1990s. British Rail first placed an order for forty-two Class 37 locomotives in January 1959, the first of which was delivered in November 1960, entering service on 2 December with the last of this original batch complete by mid-1962, by which time subsequent orders had been placed. The last of the 309 locomotives built was delivered to the Western Region on 9 November 1965, originally numbered in the range D6700-D6999 and D6600-D6608. Many Class 37 Locomotives were refurbished in the 1980s, extending their life.

As a result, the Class 37 remains in service to this day as one of the longest serving classes on British railways. Second-hand locomotives have been exported to railways in France and Spain whilst in the UK many locomotives no longer required to work have been preserved. Network Rail possesses 5 Class 37 locomotives. One of these, No. 37217, is in storage whilst the other four have undergone extensive refurbishment. The refurbished locomotives have been reclassified Class 97/3, with the Class 97 designation reserved for departmental locomotives under the TOPS system. These four were used by Network rail as part of the European Rail Traffic Management System (ERTMS) trial project on the Cambrian Line. The class was chosen because of its original fitment with both air and vacuum braking, a feature which will allow them to pull both modern freight trains as well as steam specials.

Entering service as the English Electric Type 3, the British Rail Class 37 diesel locomotives were built at the Vulcan Foundry in Newton-le-Willows in a Co-Co configuration, based on locomotive designs for export markets. Built to undertake both freight and passenger work across all BR sectors, these engines proved highly reliable and, after overhaul, many survived in service across the network into the 1990s. British Rail first placed an order for forty-two Class 37 locomotives in January 1959, the first of which was delivered in November 1960, entering service on 2 December with the last of this original batch complete by mid-1962, by which time subsequent orders had been placed.

The last of the 309 locomotives built was delivered to the Western Region on 9 November 1965, originally numbered in the range D6700-D6999 and D6600-D6608. Many Class 37 Locomotives were refurbished in the 1980s, extending their life. As a result, the Class 37 remains in service to this day as one of the longest serving classes on British railways. Second-hand locomotives have been exported to railways in France and Spain whilst in the UK many locomotives no longer required to work have been preserved. Rail Operations Group operate a fleet of 6 locomotives built between 1961 and 1963. They have been modified to allow them to move EMUs around the network including modifications to allow them to couple with and operate the brakes on various EMU classes without the need for translator vehicles. Built in 1963 the locomotive was initially numbered D6812 but became No. 37112 under TOPs in 1974. The locomotive was updated to Class 37/5 specification in 1985 and was renumbered 37510.

Built in 1961 and 1962, the Class 55 Co-Co diesel locomotives were specifically designed for the high-speed express passenger services on the East Coast Main Line (ECML). The Class, built by English Electric, was powered by two 18-cylinder D18-25 series II type V Deltic engines, each rated at 1,650 hp continuous at 1500 rpm. This unique engine also powered the DP1 prototype that preceded the Class 55s, with the prototype being named ‘Deltic’ after its engines, hence the Class 55 also became known as ‘Deltics’.

After the introduction of the HSTs, the Class 55s were deposed from many of their express duties, instead being placed on secondary services. It soon became clear that maintaining the Deltics for these secondary duties would not be economically viable meaning that the class were run with minimal maintenance until they failed, at which point they would be sent to Doncaster Works to be scrapped. Six locomotives were preserved, including 55 002 ‘The King's Own Yorkshire Light Infantry’ which was selected by the National Railway Museum to join the National Collection. After privatisation of the British railway network, the preserved Deltics became ideal candidates for mainline running due to their strong performance characteristics relative to other preserved diesels. This has included running passenger charters as well as freight services. On 29 November 2017 it was announced via the official Royal Scots Grey website that 55 022 ‘Royal Scots Grey’ and D9016 ‘Gordon Highlander’, plus all spares, had been sold to Locomotive Services Limited, with D9016 recently moving to LSL’s facility in Margate. Built in 1961, locomotive No. D9013 was allocated to the Haymarket shed from new and spent most of its life there other than a brief allocation to Finsbury Park in early 1968 which lasted just four months. The locomotive served with BR until its withdrawal from service in December 1981.

The Class 59 is a Co-Co diesel-electric locomotive built by Electro-Motive Diesel in La Grange, Illinois for British customers. A tender for six locomotives was created by Foster Yeoman, operator of Torr Works, for a powerful locomotive with 95% availability. Although Brush Traction and BREL of Britain were invited to come up with a design, only EMD could be the 95% availability criteria. EMD’s tender was sufficiently adept at the work required that double heading would no longer be needed, resulting in the order being reduced to just 4.

The locomotives were delivered to the UK via Southampton in January 1986 becoming the first privately owned locomotives to regularly operate on Britain’s mainline and the first designed and built in the US. After the initial 4 locomotives were proven successful, the Amalgamated Roadstone Corporation (ARC) ordered another 4 which were built by General Motors Diesel Division at their Canadian plant in London, Ontario in 1990. A final order of six locomotives was placed by National Power which were again built in Ontario in 1994 and 1995. The hugely successful EMD Class 66 is partially a development of the Class 59 and shares many components including its bodywork. Locomotive No. 59101 was one of the 4 ARC locomotives to be built in Canada. The locomotive arrived in Britain in October 1990 and entered service the following month. By the time the locomotive had arrived ARC had been purchased by Hanson PLC and as a result over the next few years all four of the ARC order locomotives were repainted into the blue and white Hanson livery.