The British Rail Class 308 alternating current (AC) electric multiple units (EMU) were built by British Railways' Holgate Road carriage works in three batches between 1959 and 1961. They were initially classified as AM8 units before the introduction of TOPS.

The first batch of 33 units were built in 1959, classified as AM8 and numbered 133–165. This was later changed to Class 308/1 under the TOPS system, and units were renumbered 308133–165. Each unit was formed of four carriages: two outer driving trailers, an intermediate trailer, and a motor coach.

A second batch of nine units, numbered 313–321, were built in 1959–60. These units were later reclassified as Class 308/2 under TOPS. Each unit was formed of four carriages: two outer driving trailers, an intermediate trailer, and a motor luggage van

Finally, a third batch of 3-car units were built in 1961 for suburban services from London Liverpool Street to Chingford and Enfield Town. They were numbered 453–455, following on from the Class 305/1 units, which also operated these services. These units were later reclassified as Class 308/3, and renumbered 308453–455 under TOPS. Each unit was formed of three carriages: two outer driving trailers, and an intermediate motor coach. 

One driving trailer from unit 308136 has been saved for preservation.

The carriage has been stripped of asbestos, and the full internal rebuild was abandoned in favour of housing the salvaged parts of the London Underground Victoria Line Cobourg Street signalling centre, and much of the former Brixton interlocking machine room equipment. The Cobourg Street equipment is now partially working, with work ongoing to allow simulated train movements to be displayed.