The British Rail Class 508 (or 4PER) is a type of electric multiple unit (EMU) passenger train built by British Rail Engineering Limited, at Holgate Road carriage works, York, in 1979 and 1980. They were the fourth variant of British Rail's standard 1972 design for suburban EMUs, eventually encompassing 755 vehicles and five classes (313/314/315/507/508). They have worked mostly on the Merseyrail network since 1983 and continue to do so, having been refurbished by Alstom's Eastleigh Works. The Class 508 unit is now years old. Description The class was developed for Merseyside, following extensive trials and testing of the 4Pep/2Pep stock that was built in the early 1970s. Testing of Class 313 took place on the Northern Line on Merseyside, using 313013/063 which were loaned from the Great Northern Line of the Eastern Region to Hall Road TMD. Original plans were drawn up for 58 Class 508s to be constructed, although costing issues limited the eventual number to 43. However, following planning and building, British Rail decided to divert the 508s to work alongside much older first-generation 4Sub EMUs in the London Waterloo area. The first unit was delivered to Strawberry Hill depot on 9 August 1979. Based at Wimbledon Traincare Depot, they soon became problematic due to their non-standard dimensions and brake problems caused by leaf fall. Once a new build of Class 455 EMUs was completed, the Class 508s were sent slowly to their originally intended home on the Merseyrail network. Driver training began at Kirkdale on 17 February 1982 and the first Class 508 began service on the Northern Line the following month. The first Wirral Line service commenced on 8 June 1984 and the Class 508s had completely displaced the Class 503 fleet by the end of March 1985. The fleet was then working in parallel with the already well-established fleet of Class 507 EMUs across the River Mersey, which had been working on Merseyside since 1978. Current operations Merseyrail Merseyrail operates 25 508s, which are used interchangeably between the Northern Line and the Wirral Line. They commonly work the following services: Southport - Hunts Cross line Liverpool Central - Ormskirk line Liverpool Central - Kirkby line Liverpool Lime Street - New Brighton line Liverpool Lime Street - West Kirby line Liverpool Lime Street - Chester line Liverpool Lime Street - Ellesmere Port line Merseyrail's fleet of Class 508 units are primarily maintained at Birkenhead North