The British Rail Class 423 (4 VEP), electric multiple unit passenger trains were mostly built by British Rail (BR) at York Works from 1967 to 1974, although the MBSOs and TSOs of the first 20, 7701-7720, were built at Derby Works. They have manually opening doors next to every seating row and were the last coaching stock built in this pattern for BR. They were mostly found working outer-suburban services in South London and rural services in Kent, Sussex and Hampshire, up to 2005 when they were finally replaced by Electrostar and Desiro units. The fleet had a working life of 38 years. Description Standard units Ordered in 1965, 194 standard four-car 4 VEP units were built between 1967 and 1974, numbered 7701-7894; subsequently becoming class 423 under TOPS. They were subsequently renumbered in the 1980s into the 30xx and 31xx series in order to make numbers TOPS compliant. Between 1988 and 1995 the units were internally facelifted. The work involved fitting fluorescent lighting and public address equipment, and also rebuilding the MBS (motor brake second) vehicles with an additional two bays of seating in space formerly used for luggage. On refurbishment only the first 20 units were renumbered in order, in the 34xx series. All other units were renumbered from 3421 onwards, in the order they were refurbished. All units ended up swapping motor vehicles on refurbishment - the additional work on these cars made the work take longer than that carried out on trailer vehicles. 8 VAB unit In 1968, due to a shortage of suitable stock for the Bournemouth electrification scheme, BR formed an eight-carriage 8 VAB unit, no. 8001. The unit was formed of carriages from three standard sets, nos. 7739/41/42, plus a conventional locomotive-hauled buffet carriage. Three MBSOs were required within the make-up as the standard 'TRB' was not through-wired for traction power distribution. In view of this the two MBSOs in the five-car portion had collector shoes fitted to one bogie on each. The unit worked on occasions with a 4TC; this usually had a Class 33 attached to provide ETH and train lighting in the TC unit, as the 8 VAB was not fitted with ETH jumper cables on the unit ends. Its normal running formation was with another 4 VEP to make a 12-car set. The 'TRB' vehicle retained its gas-powered appliances so, unlike 4 REP buffet cars, was able to provide