The
4EPB units (
4-car
Electro-
Pneumatic
Brake) were a development of the
Southern Railway (SR) 4Sub design, but incorporating
electro-pneumatic brakes, unit-to-unit
buckeye couplings,
roller blind headcode displays in place of the stencil holders used previously, a revised front and without external doors to the driver's cab – access was via the adjacent guard's compartment. There were
motor-generators for the lighting and current control whereas previous practice had been to use
series lighting and a
voltage divider for the control circuits. The first units built were designed by
Oliver Bulleid and as a consequence were based on
Southern Railway designs and utilised standard Southern railway
jigs, being constructed using standard Southern Railway components such as doors and being built to a standard Southern body profile; they were mounted on underframes reclaimed from older cars, the wooden bodies of which were scrapped. The doyen of the class, unit 5001, was completed at
Eastleigh in 1951. Further examples were built at Eastleigh up until 1957. Altogether, 213 units were built: in 78 of the units, one car was a former 4-SUB trailer rewired to operate with 4-EPB stock. The motor bogies of cars 14001–106 (units 5001–53) were known as the "eastern" type, and had a wheelbase of ; those of cars 14201–520 (units 5101–5260) were known as the "central" type, and had a wheelbase of . The "eastern" motor bogies were later replaced by the "central" type, the process being completed in 1964, but the cars (and units) were not renumbered. The formation of each unit was similar to the later 4-SUB units. That is, there were two driving motor brake third open cars comprising a driving cab, guard's compartment and eight-bay passenger saloon having 82 seats; between these were a trailer third having ten compartments providing 120 seats (cars 15005 and 15038 had nine compartments seating 108) and a trailer third open having ten seating bays providing 102 seats. The total capacity of each unit was accordingly 386 seats, except units 5005 and 5220 which seated 374. Third class was renamed second class in 1956, and the car designations became driving motor brake second open (DMBSO), trailer second (TS) and trailer second open (TSO). In 1960, the first British Railways design units appeared. Intended to replace the 1925 design Southern Railway suburban electric stock, these units were based on
British Railways Mark 1 coaching stock with a different body profile and underframe length from the earlier Class 415 units. The first two units (5301/02), however, were composed of Mark One profile Driving Motor Brake Seconds and Southern Railway profile intermediate vehicles. Unit 5303 was the first to sport intermediate trailers of Mark 1 profile. Two units differed from the rest of the batch in featuring B5 (S) bogies to enable use on peak hour commuter trains to
Eastbourne. Reformations over the years, following accidents and incidents, led to a few units becoming composed of a mixture of original design stock of Southern Railway outline and the later, Mark 1 based, British Railways stock. In the earlier, Southern-style 5001–5053, 5101–5260 series, most units (all of which were one class only) comprised a driving motor open saloon including brake at each end of the set, sandwiching a trailer open and a high-density (6 per side) trailer ten-compartment vehicle with access from the passenger doors only; there was no gangway down the coach. A very small number of these 4-EPBs comprised either two open-trailers or two compartment-trailers. A small number of the trailers had been built as 'composites' – a mixture of First and Third Class – and were later fitted out as 9-compartment one-class vehicles but with the former 1st accommodation still identifiable with extra-wide compartments. In the mid-1960s, a number of compartments were marked as women-only, because of the density of cigarette smoke at rush-hour in the general compartments, but as these were not well-regarded they were withdrawn in the late 1960s in favour of non-smoking cars, marked by red triangles on the windows. At first one car per set was allocated to non-smoking, but soon one driving car and one trailer in each set were the norm. The production vehicles in the BR series 5301-5370 had slightly higher capacity motor coaches, identical vehicles at each end of the set, with an internal partition splitting the saloon into two smaller ones, and a pair of identical trailers each comprising 5 compartments and a 5-bay open saloon, with the compartment end of each coach always back-to-back with its neighbour. However, on 23 March 1988,
a woman was found murdered in a compartment EPB car on an Orpington/London Victoria working which led to
Network SouthEast reconfiguring the then-remaining unrefurbished SR-design 4-EPBs; as a result all compartment stock ran limited workings in busy periods and had a red stripe at the cantrail (the place where the bodysides meet the roof). This stock did not work in service after 8pm and was known as 4COM. These units, being heavier than the EPBs were retained for the winter of 1988/1989 to run overnight keeping the tracks clear of snow. Most British Rail Class 415 units were withdrawn in the mid-1980s, owing to their partial replacement by newer stock such as the
British Rail Class 455 units and the fact that many units contained
asbestos. However, a significant number of the units were "facelifted". The asbestos was removed and the units' interiors were improved. This resulted in some re-numbering of stock, so that the earlier units built in the style of the Southern Railway became the 54xx series whilst the British Railways style units became the 56xx series. Some of the 56xx series units received express gear ratios to allow them to work services between
London and
Kent Coast destinations. Although all the non-refurbished BR Class 415/2s were withdrawn, three Class 415/1s of Southern Railway outline survived until the final withdrawal of Class 415 stock in 1995. These units included 5001, the first unit constructed, and 5176. Both of these units were repainted into liveries previously carried by the class, 5001 receiving British Railways green livery with yellow warning panels and 5176 receiving British Rail blue livery with full yellow ends. ==Interior fittings==