The British Rail Class 317 electric multiple unit (EMU) passenger trains were constructed by British Rail Engineering Limited in two batches: 48 sets were produced in 1981–1982 and 24 sets in 1985–1987. They were the first of several classes of British Rail EMU to be based on the all-steel Mark 3 bodyshell, departing from the PEP-aluminium design which had spawned the earlier Class 313 to Class 315, Class 507 and Class 508. The Mark 3 bodyshell was also the basis of Class 318, Class 455 and the diesel Class 150. The Class 317 uses overhead alternating current electrification. All units were withdrawn in July 2022.