The British Rail Class 312 alternating current (AC) electric multiple units (EMUs) were built between 1975 and 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, as well as the last class of multiple unit to be built with slam doors in Britain. These features contributed to their relatively early withdrawal at 25–28 years old, compared with a typical EMU life expectancy of 30–40 years.