The British Railways English Electric Type 3 diesel locomotives were commissioned as a part of the 1955 British Railways modernisation plan. In total 309 were built, with the order split between English Electric's Vulcan Foundry at Newton-le-Willows and Robert Stephenson and Hawthorns, Darlington.

The Class 37 became a familiar sight in many parts of the British Rail network providing power for secondary Inter-City services in East Anglia, the Midlands, the South West and Scotland. They were equally at home on freight services where they performed well for many years.