The British Rail Class 421 (4CIG) electric multiple units were built at BR's Holgate Road carriage works between 1964 and 1972.Units were built in two batches, and were initially introduced on services on the Brighton Main Line.The standard units contained only passenger accommodation, and formed the bulk of the fleet.In 1983, two temporary 8Mig units, given the TOPS classification Class 482 and numbered 2601–2602,[3] were formed while the 4Big fleet underwent asbestos removal.Therefore, four standard 'Phase 2' 4Cig units, numbers 7401–7404, were reformed with a conventional locomotive-hauled miniature buffet carriage (RMB).The three former SR division – South-Eastern, South Central and South-Western – all operated 4Cig units, and are dealt with separately here.South Eastern Trains (SET) operated a small fleet of three 'Phase 1' and 22 'Phase 2' 4Cig units.The three 'Phase 1' units were painted in white undercoat livery, since their use was originally only supposed to be short-term.The remaining eleven unit were heavily rebuilt at Eastleigh Works, with compartments removed and opened out, and the buffet carriages withdrawn.From 2003 Southern started to replace its slam-door fleet with new Class 377 Electrostar units.South West Trains inherited a small fleet of twelve 'Phase 2' 4Cig units, and the larger fleet of 22 "Greyhound" units which had been modified to cut several minutes from journey times on the Portsmouth Direct line with its 1 in 80 gradients by adding a second stage of field weakening to improve performance at higher speeds (17% at 54 mph, 30% at 90 mph).The modifications included the removal of the buffet carriages, which were replaced by spare intermediate trailers from mechanically similar 4Cep units.These trailers were immediately recognisable since although they had the same body profile as the rest of the unit the windows were different and they had InterCity70[jargon] seating.It was reclassified as Class 421/7, renumbered 1499, and dedicated to the Lymington Branch Line service, where it replaced the previous incumbent unit, no.The final slam-door service ran on 26 May from London Waterloo to Bournemouth using units 1396, 1398 and 4Vep 3536.As stated in the relevant timetable, "The slam door trains will be remembered with affection as they pass into history."
Class 421/4 1860 in Connex South Central livery at St Denys
Class 421/8, no. 1396, at
Clapham Junction
on 19 July 2003. This unit is one of eight "Greyhound" units converted from redundant 4Big units for use by
South West Trains
. The buffet coach was replaced with a spare
4Cep
trailer vehicle, which is identifiable by its different windows as the second vehicle in the unit.
The last day of operation on the Lymington Branch Line
Phase 2 4CIG 7346 after running away at Wimbledon in 1974