The British Rail Class 312 is a type of alternating current (AC) electric multiple unit (EMU) built in 1975-1978 for use on outer-suburban passenger services. It was the last class of multiple unit to be constructed with the British Rail Mark 2 bodyshell, and also the last with slam doors. This latter feature contributed to their relatively early withdrawal (25-28 years old, compared with a life expectancy of 30 years).