The British Rail Class 411 (4CEP) 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 411 design included the class 410 and class 412 4 BEP units, which 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. They were replaced by Juniper, Desiro, and Electrostar units. The fleet's lifespan was 49 years. These units are the longest-lived BR Mark 1 EMUs. Description A total of 133 units were built, as two different types. The majority of units were 'standard' passenger-only units, complemented by units containing a buffet car. Standard units The standard units contained passenger seating only, and formed the backbone of the new fleet. 111 units were built in several batches, initially numbered in the range 7101-7211. Units 7101-7104 were the prototype units, and were followed by 'Phase 1' units (7105-7153) and subsequently 'Phase 2' units (7154-7211). Units were formed of two outer driving motors cars with 2nd class (later Standard Class) seating in open saloons, sandwiching two intermediate trailer cars – one a corridor second and the other a First/Second corridor composite. 4 BEP units 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. Vehicle numbering The numbering of individual vehicles and details of when units were built are shown in the table below. Refurbishment During the late 1970s and early 1980s, British Rail recognised that the 4 CEP fleet was in need of refurbishment. This was carried out at BR's Swindon Works. Refurbishment included moving the guard's compartment from both the motor cars