The British Rail Class 412 (4BEP) electric multiple units were built at Eastleigh works from 1956–63 for the newly electrified main lines in Kent. These units, which used a British Railways Mark 1 bodyshell, were based on the earlier Southern Railway 4 COR design, built in 1937. Variants of the class 412 design included the class 411 (4CEP) and class 412 4 BEP units, BEP units contained a buffet car in place of a standard trailer. They were later used on services in Sussex and Hampshire; following the privatisation of British Rail in 1995, the units were used by the Connex South Central, Connex South Eastern and South West Trains franchises.

The 4 BEP units were similar to the standard units, but contained a buffet car in place of the second class open trailer. The buffet trailer had a dining room, a large kitchen pantry, and a buffet counter with some seats. 22 units were built, initially numbered in the range 7001-7022. The first two units (7001-7002) were prototypes, and were followed by 'Phase 1' units (7003-7012) and 'Phase 2' (7013-7022).  The 4 BEP fleet were classified as Class 410 by British Rail under the new computer numbering system introduced in 1968.

In 2002, the buffet cars from the 4 BEP units were inserted into seven standard 4 CEP units, which were renumbered 2321–2327 (reclassified as Class 412/2). The displaced carriages were inserted into the 4 BEP units, which were renumbered 2311–2317 (reclassified as Class 412/1). The reason behind this was that the 4 BEP units had faster acceleration, and the buffet cars were no longer used. Therefore, the reformations allowed a higher seating capacity in the faster units.