Class 37 locomotive

A reader consulting an Ian Allan ABC in the early 1960s would have found this locomotive listed as the English Electric Type 3, a Co-Co diesel-electric that the TOPS scheme later renumbered as Class 37. It became one of the most widely used and longest-serving diesel designs on British Railways, and a good number remain at work on the main line and in preservation today.

Design and build

English Electric built 309 of the type between 1960 and 1965, work being shared between the company’s Vulcan Foundry at Newton-le-Willows and Robert Stephenson and Hawthorns at Darlington. Power came from the English Electric 12CSVT engine, rated at about 1,750 horsepower, driving the six axles through the Co-Co arrangement. The design followed the general pattern of English Electric’s other Type designs of the period and proved unusually durable in traffic.

In service

The class worked across every region of British Railways but became especially associated with East Anglia, South Wales, and the Scottish Highlands, handling both freight and passenger duties. Enthusiasts nicknamed them “tractors” and “growlers”, and the earlier split-headcode nose-end examples remain much liked. Reliability and a wide route availability kept them in demand long after many contemporaries had gone.

Numbering

Most of the class was numbered in the D6700 series, with a small earlier batch carrying numbers in the D6600s. Under the TOPS renumbering scheme of the 1970s the type became Class 37, the identity by which the surviving locomotives are known today.

Withdrawal and preservation

The class proved exceptionally long-lived, and withdrawal was gradual rather than sudden as newer types displaced them. A number remain in main-line charter and departmental use to this day, which is unusual for a design of this age. Around thirty examples survive in preservation or in traffic.