British Rail Class 310

The BR Class 310 was a fleet of fifty four-car 25 kV AC electric multiple unit sets built between 1965 and 1967 at BR Derby Works, designed for the West Coast Main Line suburban and outer-suburban services that were being electrified as part of the WCML electrification programme extending beyond London to Birmingham, Manchester, and Liverpool. The Class 310 was the first purpose-built AC electric suburban unit for the WCML and established the pattern for the outer-suburban electric fleet that would work the route for the following three decades.

Each four-car set consisted of a Driving Motor Brake Standard (DMBS), two Trailer Standards (TS), and a Driving Trailer Composite (DTC), giving a mixed-class formation with first and standard class accommodation suited to the outer-suburban and commuter markets of the West Midlands and the northwest London hinterland. Power was collected from the 25 kV 50 Hz overhead catenary via a roof-mounted pantograph, and the original electrical equipment used tap-changer control of the traction motors — the standard technology for AC EMUs of the period before the introduction of thyristor control in later generations. The maximum speed was 90 mph, appropriate for the semi-fast and stopping services the class was designed to work.

The fifty sets entered service from 1966 on Euston–Bletchley–Birmingham New Street outer-suburban services and West Midlands local services, replacing locomotive-hauled coaching stock that had previously worked these routes. The Class 310s served reliably through the late 1960s and 1970s, their four-car formation well matched to the peak-hour loadings of the Birmingham and Manchester commuter flows. Network SouthEast and subsequently Regional Railways inherited the fleet through the sector and franchise changes of the late 1980s and early 1990s.

Withdrawal began in 1995 as the newer Class 321 and Class 323 EMUs arrived on WCML services, and the last Class 310s were retired in 2002. The fleet gave over thirty-five years of service, a creditable record for what had been designed as the first generation of WCML suburban electric stock. None was preserved, despite the class's historical importance as the original WCML suburban EMU.