Originally starting life as Class 510, the Class 455/8 was introduced in 1982 to replace the aging 4SUB and 4EPB units. Class 455/8s were part of the first batch of units to be delivered between 1982 and 1984. All 46 Southern Units were allocated to Stewarts Lane Depot and 28 allocated to South West Trains at Wimbledon Depot. Formed of four vehicles, a Driving Trailer Second Open at each end, a Motor Second Open and Trailer Second Open in between, the Class 455/8 differed in a number of ways to Class 455/7 and Class 455/9 units.