The DVT vehicles were built in 1988 to form push – pull sets with West Coast Main Line Mk3 vehicles. They provide full train control via a TDM multiplex system using the lighting “RCH” plugs on the vehicles, thus avoiding rewiring. Usually used with Class 86, 87 or 90 locomotives, they also provide van space, but this is rarely used since the end of the “Red Star” parcels business. Two large sliding doors each side provide access to this space. A small office area is provided for the train manager, with a public address point. Although apparently empty, they are ballasted under the floor and weigh 45 Tonnes. BR “series 4” disc-braked bogies are used, similar to the Class 158 units. Most of these vehicles are now off lease.