They were originally intended mostly for freight work but, with good foresight by Southern Region, were fitted with electric train heating - indeed the lack of a need to carry a boiler for steam heat allowed a more powerful diesel to be fitted in the same body shell as the earlier locomotives . They were often to be found on passenger services on the Kent Coast and to Bournemouth and elsewhere.
|Builder:||Birmingham Railway Carriage & Wagon Company|
|Engine:||Sulzer 8LDA28 diesel|
|Power:||1, 550 hp (1, 156 kW)|
Most Class 33s were in the standard 33/0 sub-class, however a number were also fitted for push-pull operations as 33/1 and operated with the 4-TC (Class 438)  though could also work with any SR Electro-Pneumatically controlled multiple units and locomotives. A batch of locomotives was also reduced in width by 178mm for operation on the Hastings Line with its restricted clearances as the 33/2. Sadly the expense and effort in modifying the design for what turned out to be a small batch of locomotives is said to have contributed to BRCW's bankruptcy in the mid-1960s.
Nowadays only a handful of the locomotives, known as Cromptons by enthusiasts after the Crompton Parkinson electrical equipment installed in them, remain in mainline use with the West Coast Railway Company however twenty-nine have been preserved covering all three sub-types.
|33 035 at Ropley|
|Cab of 33 103|
|33 204 at Stewarts Lane in 1988, KD Collection|
|33 103 at Wirksworth|
|Class 33 undergoing maintenance at Stewarts Lane 1988, KD Collection|
|33 035 at Kidderminster|
 Brian Haresnape, Production Diesel-Electrics Types 1-3 (Ian Allan, 1983) p. 58
 David Brown, Southern Electric Vol 2 (Capital Transport, 2010) p. 215
 John Vaughan, Diesels on the Southern (Ian Allan, 1980) p. 33