The British Rail Class 315 was a fleet of alternating current (AC) electric multiple unit (EMU) trains, built by British Rail Engineering Limited at Holgate Road Carriage Works in York between 1980 and 1981; they replaced the Class 306 units. It was the fifth and final variant of unit derived from British Rail's 1971 prototype suburban EMU design which, as the BREL 1972 family, eventually encompassed 755 vehicles across Classes , , 315, and . Revenue services with Class 315 units commenced in 1980 and continued until December 2022. Description Each Class 315 unit is formed of four vehicles; ---DMSO. Up to three units can be used together in service for a maximum 12-car formation. Each DMSO vehicle carries four DC traction motors, each of for a total power output of per unit. The order included an element of dual-sourcing 41 units (315801–315841) were fitted with electrical equipment from Brush Traction, while equipment for the remaining 20 units (315842–315861) was provided by the General Electric Company (GEC). The traction motors are interchangeable between equipment providers. The DMSO vehicles also carry the air compressors and main reservoirs that provide the braking and suspension air supplies. The air supply was originally additionally used to operate the passenger doors, but this system was later replaced by an all-electric one. The PTSO vehicles carry the main and auxiliary transformers, auxiliary batteries, the Stone Faiveley AMBR Mk.1 pantograph, and the main circuit breaker, while the TSO vehicles only provide passenger accommodation. Seating is standard-class only and there are no toilet facilities provided onboard. As-built, each four-car unit had seats for 318 passengers, but this was reduced to 309 plus seven tip-up during a refit in 2012 Vehicles are numbered in the following ranges: DMSO: 64461–64582 PTSO: 71281–71341 TSO: 71389–71449 Operations Following the privatisation of British Rail, the Class 315s were divided between First Great Eastern (43 units) and West Anglia Great Northern (18 units). The leasing company Eversholt Rail Group has owned the entire Class 315 fleet since privatisation. One / National Express From April 2004, National Express East Anglia (NXEA) ran the inaugural Greater Anglia franchise, which combined the previous operations of both First Great Eastern and West Anglia Great Northern and thus combined the two Class 315 fleets. The franchise was initially known as 'One' but was rebranded National Express East Anglia (NXEA) in February 2008. NXEA contracted with Bombardier to refurbish all