In the early 1990s, the British Rail parcels sector Rail Express Systems identified the need for driving trailers to operate in push-pull mode with a locomotive. This would remove the time-consuming process of changing the locomotive to other end of the train to allow it to leave a terminus. These new vehicles were called Propelling Control Vehicles (PCVs), since it was envisaged that they would only be used to propel a train into or out of a terminus, and not used at high speed or over long distances.