British Railways Southern region inherited a network of electrified routes south of London along with plan for the expansion of the electrification. Steam locomotives were still needed for freight trains and passenger services beyond the electrified areas to Southampton, Portsmouth, Bournemouth and into the South West of England. To replace steam traction the Southern requested a diesel locomotive capable of supplying electric power for heating coaching stock, instead of steam as used on other regions. The Birmingham Railway Carriage and Wagon company offered a version of their type 2 locomotives which later formed classes 26 and 27, with the removal of the steam generator allowing the bodyshell to accommodate the 8 cylinder version of the Sulzer LDA engine, boosting output to 1,550bhp from the 6 cylinder power units 1,250bhp. This provided the extra power required for the electric heating supply without significantly compromising the power available at the rail and creating a very useful general service freight locomotive.
The elimination of the rarely used cab-front connecting doors also allowed the cab ends to be given full-depth central windows, greatly improving the locomotives' appearance and allowing the route indicator to be positioned in the central window.
A number of variants were created, including the push-pull equipped class 33/1 which was fitted with EMU control jumpers, allowing the diesel to be remotely operated from a EMU train control cab. This small sub-class was used on the Weymouth extension of the London to Bournemouth trains, taking forward a set of BR Mk1 coaches fitted driving cabs for use as EMU trailer sets. When spare from these duties the 33/1 locomotives were also used in the general pool.
Throughout their lives the class 33s reached far beyond the Southern region, duties including hauling inter-regional block freight trains through to destinations as far North as Doncaster and after taking over the long-established Cardiff - Portsmouth cross-country trains the duty cycle included daily services north from Cardiff to Crewe, Manchester and along the North Wales coast.
Dapol manufacture N gauge models of the class 33 representing classes 33/0 and 33/1 and feature :
- Detailed body with etched grilles and separately fitted handrails
- RP25.72 profile darkened wheels with pin-point bearings
- 5 pole Super Creep motor with huge pulling power and incredible slow running speed
- All wheel drive and pickup
- Independently controllable directional lighting
- DCC Ready with NEXT-18 decoder socket
- Dapol low-friction mechanism for efficient quiet running
- Heavy split frame chassis for excellent running and haulage qualities.