The CEP in the coding stands for 'Corridor Electro-Pneumatic' - the latter referring to the brakes. They were built in 1956-63 by BR at Eastleigh as express commuter trains. 111 4-car units were produced and were originally numbered 7101 to 7211. They were a development of the Southern Railway 1937 built 4-COR units. The 4-CEPs were built for the Kent Coast electrification scheme and were based on the Mk1 coach design.

The first four units were used initially from 1956 on Central Division services. Operating on the British Railways Southern Region 650/750 volts DC third rail system. The units replaced steam operation on services to Margate, Ramsgate, Dover and Folkestone. All units were refurbished at Swindon Works between 1980 and 1983 and were subsequently renumbered in the series 1501 to 1621, the additional units being provided from 4-BEP (Class 410) units.

Post privatisation, the units saw service with Connex SouthEastern (later South Eastern Trains), Connex South Central and South West Trains. The first unit was withdrawn in 2002 and the last in 2005. Several vehicles have been preserved.

The Bachmann model initially depicts the vehicles in the original condition as running between delivery and refurbishment. It utilises many components from the Bachmann Mk1 CK and SCK vehicles, but has authentic bogies, lit indicator boxes and new roofs.

In developing the model, Bachmann worked with the Southern Electric Group for some time. It is released as a 4-car set and is 'DCC ready'. It is essential for the cars to be assembled in the prescribed order or the unit will not work as the continuous electical circuit will be broken.

Although awaited for rather a long time, due to difficulty in obtaining drawings, there is no doubt that the model was well worth waiting for. It is exquisite I every detail, with full under-floor equipment, illuminated headcode boxes, a dedicated coupling system and internal lighting with LEDs.