Class 312 (BR York, LMR and ER Outer Suburban Services)

The Class 312 Electric Multiple Unit was based on the earlier Class 310 and built for the Great Northern Line from London Kings Cross to Royston, the Great Eastern and also four sets for the West Coast Main Line [1]. The Class 312 was the last Mark 2 based EMU to be built by British Rail. It was also the last new build with slam doors to be built.

78037 preserved in NSE livery

Information
Number built:	196 (49 4-car sets)
Built:	1975-78
Builder:	BR York
Engine:	4 EE546A traction motors (6.25 (312/1 only) / 25kV AC OHLE)
Power:	1, 080 hp (810 kW)
Formation:	Battery Driving Trailer Standard Open Lavatory (BDTSOL)+ Motor Brake Standard Open (MBSO)+Trailer Standard Open (TSO)+Driving Trailer Composite Open Lavatory (DTCOL)

Twenty six sets were initially allocated to the Great Northern as 312/0 but they were transferred to the Great Eastern due to their unsuitability for driver only operation [2]. Sets for Great Eastern London Liverpool Street services were fitted for dual voltage (6.25 as well as 25 kV AC) as 312/1. The WCML sets (312/2) were restricted to 75mp/h running so they could run in multiple with the Class 310. When they were later transferred to join the rest of the fleet on the Great Eastern the speed restriction was removed.

By the end of the 1980s the fleet was concentrated on the Great Eastern and London, Tilbury & Southend Railway. In the privatised era some returned to the WCML and were operated by Central Trains, the rest were operated by c2c, First Great Eastern and LTS Rail. 

At the turn of the century they were gradually withdrawn from service with the last being withdrawn in 2004, the fact they were Mark 2 based and having slam doors meaning they had shorter lives than some EMUs have had. Two cars have been preserved.

The other preserved car 71205

[1] Colin J Marsden, DMU and EMU Recognition Guide (Ian Allan, 2013) p. 232
[2] Alec Swain, Overhead Line Electric Multiple Units (Ian Allan, 1990) p. 59