The Class 47 was built between 1962 - 67 as the Brush Type 4 by both Brush Traction and British Railways Crewe works, eventually numbering 512 examples. It was designed by Brush as a mixed traffic locomotive with a maximum speed of 95mph and fitted with a Sulzer 2750bhp diesel engine. Batches were constructed with electric train heating (ETH) equipment, steam heating, or no heat provision intended for freight use, though many were later fitted with ETH as steam heating of passenger trains was eliminated. The Class soon was to be seen working all types of trains across the network, though it was not without its problems, the most major resulting in the derating of the engine to 2580bhp. Today, a small number of 47s remain in main line service though generally on relatively light duties compared to that which they once worked, and further examples have entered preservation. By the 1990s and the privatisation of British Rail considerable numbers were being withdrawn as life expired and many of those remaining were becoming increasingly unreliable. In 1997 the newly formed operator Freightliner decided to begin to address the problem by rebuilding 12 locos with secondhand General Motors engines ( the Sulzer power unit being one of the biggest weaknesses) and alternators. The body and running gear remained the same and the locomotives were classified as 57.

These were very successful, and remain in service today with DRS and West Coast Railways. Following the success of the 57/0 as they became, a demonstrator loco was converted fitted with ETH and a restyled front end. Numbered 57601 it was painted in a purple livery and like its predecessors proved a success, leading to an order from First Great Western for 4 largely similar machines to replace 47s on the Sleeper services, and Virgin for 16 locomotives (the 57/3) to be used to haul the Pendolino sets to destinations off the electrified network and for rescue duties. Today, the FGW examples continue to perform the same work, but the 57/3s are now operated by DRS and West Coast Railways on various duties.