Over the years a huge number of ex-revenue earning electric multiple and diesel multiple unit vehicles have entered internal railway operation use. These are usually known as Departmental vehicles. On the Southern Region, where electric multiple units operated from L&SWR days, dozens of vehicles and complete sets have entered departmental use, being used for de-icing of the third rail, moving stores between depots and acting as depot tractors to name but a few. In many cases, especially with the de-icing fleet, vehicles were further adapted as new technology emerged, such as 'Sandite' laying used to keep rails clear of contamination, thus reducing wheel slip/slide.

A number of coaches/sets under the departmental banner have been involved in major traction development operations, involving both power systems or brake refinement. This has included running 1972-design EMU stock bogies under former Class 501 driving cars, right up to more recent times when some former Class 310 and VEP stock was involved in traction development for the Hitachi Class 395 fleet.

Today, a number of Network Rail test vehicles have been adapted from former EMU coaches, many previously used on the loco-hauled Gatwick Express operation. On the DEMU front, several ex-Southern Region sets and coaches passed to departmental use. A considerable number of first generation DMMU sets and individual vehicles have entered departmental service, being used for a diverse range of operations, including stores delivery, de-icing, rail head cleaning and traction development. Other sets have been rebuilt as sophisticated track and infrastructure test trains. Some purpose-built vehicles are also in use, such as the Class 150/1 outline Network Rail Class 950 unit No. 950001.

I do hope readers will enjoy looking at and reading about the diverse number of former passenger carrying EMU and DMU vehicles which have operated under the departmental banner.
Colin J. Marsden, Editor