The Class 313 units were the oldest EMUs operating on the National Rail network in Great Britain prior to their withdrawal in 2023, having entered service in 1976.

[13] The Class 313 fleet was correspondingly ordered for the inner-suburban services – those making frequent stops between London and Welwyn or Hertford.

[14][17] This in turn required that a new design of EMU be developed for the Class 313 order, as none capable of running on both systems existed at the time.

[18] Given this requirement, the opportunity was taken to further develop the Class 445 and 446 prototypes that had been produced by British Rail Engineering Limited in 1971, and which were considered by BR to be "the basis of all [its] future suburban stock".

[19] This three-car arrangement, with driving-motor vehicles 'sandwiching' the trailer carrying the AC collection equipment, was subsequently adopted as the basic layout for the Class 313 design.

Given the need to use the Northern City Line tunnels, Class 313 units were built to a slightly smaller loading gauge than conventional trains.

They were of standard length and width, but the roof was lower, which was most noticeable due to the lack of a "well" for the Stone Faiveley AMBR pantograph on the centre coach.

Part of the reason was to simplify the equipment to allow dual-voltage operation, and to keep down weight by spreading the heavy transformer and motors between vehicles.

[21] Originally the heating in the motor coaches was provided by passing air over the hot traction and braking resistors in addition to conventional heaters, but this feature was later taken out of use and the pneumatic dampers were disabled.

Many people did not wait for the guard's release and gave the handle a much harder tug, which could force the door open even if the train had not stopped.

All units originally had shoebeams on the inner bogie of each motor coach, which was sufficient for third-rail duties between Drayton Park and Moorgate.

Units 313001–313016 had shoegear fitted to the outer bogies in addition, and were transferred to the Euston – Watford DC route where there are long gaps in the third rail.

[25] The unit was repainted into Network Rail's yellow house colours and internally refurbished at Alstom's Wembley Intercity Depot, to include a new driving desk, technician's workstation, kitchen and toilet facilities, and the necessary ERTMS equipment.

[28] It was expected to be used again when ERTMS was ready for testing on the Great Western Main Line,[29] but Network Rail instead listed the unit for sale by tender in January 2023.

The final day of scheduled 313 operation on the North and West London Lines was 19 February 2010, although units remained in use as ad-hoc substitutes for unavailable 378/0s.

The decision to use 313s on the Coastway lines was controversial, as they were much older and slower than the 377s and were missing certain on board facilities like air conditioning and toilets.

[32] The rail union RMT criticised the move and many publications, including the BBC, questioned the introduction of 35-year-old trains in place of much newer units.

The Director of Engineering for Beacon Rail, which owned the Class 313s, has said, "We wanted to celebrate the heritage of this special train, so the re-livery made perfect sense.

Unusually for dual voltage trains, on this stock and its replacement, the Class 717, a shunt resistor is permanently connected to the pantograph.

[47] A final railtour, operating from London King's Cross to Royston (via Welwyn Garden City) and back (via Hertford North and Moorgate) was held on 23 October 2019 with units 313134 and 313064; the DMSO vehicle of 313064 was repainted in Network SouthEast livery.

However, in early 2023, the board decided instead to designate Network Rail's unit 313121, as unlike 313201 it retains its original seating and dual-voltage running equipment.

[50] Individual vehicles are numbered in the ranges as follows:[22] The following units have carried names: Media related to British Rail Class 313 at Wikimedia Commons