To test out the technical arrangements for the Networker, a test train was used, converted from former Class 210 carriages, which were built in 1982 by Derby Litchurch Lane Works as prototype 'Second Generation' Diesel Electric Multiple Unit (DEMU), but were withdrawn after a few years.

Initially the test unit was formed for trials on the 750 V DC third rail system of the Southern Region, and was numbered 457001.

67400) has since been incorporated into a Class 455/9 DC suburban unit, replacing a damaged Trailer Second Open (TSO) vehicle.

Vehicle details are shown below: Class 316 was originally reserved in the British Rail Fleet List for an AC EMU for the Piccadilly to Victoria (Picc-Vic) underground line proposed for Manchester in the 1970s.

The specifications and some outline design proposals for the new fleet was prepared at the Railway Technical Centre but never proceeded to tender with the project cancelled.