British Rail Class 33 "Crompton"

The BR Class 33 'Crompton' was a series of 98 Bo-Bo diesel-electric locomotives built by Birmingham Railway Carriage and Wagon Co. of Smethwick between 1960 and 1962, using a Sulzer 8LDA28 eight-cylinder in-line engine and Crompton Parkinson electrical equipment, designed specifically for the Southern Region of British Railways as the medium-power diesel to replace steam on the SR's non-electrified routes in the Weald of Kent, through Hampshire and Dorset, on the Bournemouth main line, and on the freight services that served the SR's diverse network of freight depots across the South of England. The Crompton nickname derived from Crompton Parkinson, the electrical equipment supplier.

The Southern Region's requirement was distinctive: unlike the other BR regions where diesel locomotives needed to work a wide variety of routes across different operating conditions, the SR's non-electrified routes were relatively well-defined and the Class 33 was designed to work them with a power output and overall specification matched to the SR's particular needs. The Class 33 was equipped to work push-pull passenger services — propelling coaches from the rear under the driver's remote control from a driving trailer at the front of the train — which gave the SR's non-electrified services the quick turn-round capability that the electric multiple unit services enjoyed on the third-rail network.

The Class 33 gave exceptionally long and reliable service on the Southern Region, working until well into the 1990s, and fourteen examples are preserved — the highest number of any Type 2 diesel class — reflecting the widespread affection for the Crompton among railway staff and enthusiasts who worked with them on SR and Network SouthEast services.