The Class 304 was produced for BR's new electric suburban services, enabled by the first phases of the West Coast Main Line electrification between Crewe and Manchester/Liverpool/Rugby.

Following their introduction during the early 1960s, the Class 304 could be found in operation across the southern and Midland section of the West Coast Main Line.

The first fifteen units were delivered to Longsight Depot, Manchester from April 1960 as four-car sets, and were originally numbered 001-015.

While much of the passenger compartment's interior finishing was a mixture of timber and plastic, light alloys were used for several elements, such as the doors and luggage racks.

[16] Powered by 25 kV AC via catenary, a single pantograph mounted directly above the guard's compartment of the Motor Brake vehicle gathered current from the overhead catenary, which was transferred via a rubber insulated cable from the roof directly to the onboard transformer.

The main transformer also supplied an auxiliary feed at 240 V for powering miscellaneous systems on board the train, including the heating units.

The motors were protected by an automated cutoff that activated under several circumstances, including excessive oil temperatures, earthing faults, overload, and air supply failure.

[16] Glass panels covered the cab's forward section down to waist height while a pair of fully-adjustable seats, for the driver and assistant motorman, were mounted directly upon the rear bulkhead.

The driver's instrumentation was fitted upon a sloped panel behind a flat desk lined with push buttons and light switches.

Braking was provided via an air-powered arrangement, which featured a self-lapping electro-pneumatic control actuated via a single cylinder.

[16] Prior to the commencement of electric services between Crewe and Manchester, the AM4 underwent a period of testing on the Styal line.

Because of their operation on much of the West Coast main line, the units attained substantial mileage at their 75 mph maximum speed each day on their workings, unlike those employed on suburban services elsewhere.

The long period of storage was due to the difficulty in finding a home on a preserved railway for EMU coaching stock, and thus it became the last of its class to be scrapped in November 2000.