The British Rail Class 311 alternating current (AC) electric multiple units (EMU) were built by Cravens at Sheffield from 1966 to 1967.

The Class 303 units had been built by the Pressed Steel Company at their factory in Linwood, Paisley, but by the time the Class 311 was required, Pressed Steel no longer built railway carriages, so Cravens of Sheffield worked from the same original drawings, updated at a few points, to build the new trains.

Along with the Class 303, the wrap-around driving cab windows were replaced with flat, toughened glass in the 1970s to give better protection to drivers in the event of attacks by stone-throwing vandals.

Individual carriages were numbered as follows:[6] The units were built to operate services on the newly electrified routes from Glasgow Central to Gourock and to Wemyss Bay; now known as the Inverclyde Line.

[citation needed] In 2002, Railtrack donated one of the units to the Summerlee Heritage Park museum in Coatbridge, and the other was scrapped in 2003.