The British Rail Class 314 was a class of alternating current electric multiple unit (EMU) trains built by British Rail Engineering Limited's Holgate Road carriage works in 1979. They were the third class of units derived from British Rail's 1971 prototype suburban EMU design which, as the BREL 1972 family, eventually encompassed 755 vehicles over five production classes (313, 314, 315, 507 and 508). The Class 314 fleet was used to operate inner-suburban services on the Strathclyde Partnership for Transport rail network in and around Glasgow, most typically on the Argyle, North Clyde, Cathcart Circle, Paisley Canal and Inverclyde lines. The units, formed of three cars each, worked either independently or in six-car pairs. Although the fleet had undergone a number of life-extension overhauls and upgrades, it was withdrawn from service in 2018–2019 as a result of non-compliance with the requirements of the Persons with Reduced Mobility Technical Specification for Interoperability (PRM-TSI), which became legally binding at the end of December 2019. It was replaced, for the most part, by cascaded Class 318 and Class 320 units following the introduction of the Class 385 fleet. Following withdrawal, all but one unit was scrapped; the remaining unit has been converted to act as a technology demonstrator using hydrogen-powered fuel cells and was reclassified into Class 614 in October 2021. History Class 314 units were formed of two vehicles with driver's cabs sandwiching a trailer vehicles that carried the pantograph and high-voltage transformer. The 25 kV supply collected from the overhead lines by the pantograph was passed from the transformer in the intermediate trailer to four direct current traction motors mounted under each driving car. In common with the other classes of BREL's 1972 family, Class 314 vehicles were of constructed of aluminium alloy on a steel underframe and had pneumatically-actuated sliding doors. Tightlock couplings allowed units to be coupled and uncoupled by the driver alone from within the cab, a simplification compared to the coupling procedure used by the Strathclyde network's then-existing units. The sixteen-strong Class 314 fleet had been acquired for the main purpose of operating the newly-opened Argyle Line, which they did—along with the North Clyde Line—from introduction in late 1979 until October 1999. After this they were transferred to operate Cathcart Circle services on the southern side of the Strathclyde network, covering for the withdrawal and scrapping of the Class 303 fleet. A small number of Class 314