British Rail 18000 was a prototype mainline gas turbine-electric locomotive built for British Railways in 1949 by Brown, Boveri & Cie. An earlier gas-turbine locomotive, 18100, had been ordered from Metropolitan-Vickers by the Great Western Railway but construction was delayed due to World War II; a second, 18000, was thus ordered from Switzerland in 1946. It spent its working life on the Western Region of British Railways, operating express passenger services from Paddington station, London. Overview The GWR chose a gas-turbine locomotive because, at the time, there was no single-unit diesel locomotive of sufficient power available. The King class steam locomotive could deliver about at the rail. The LMS diesel locomotives had engines of only . After allowing for transmission losses, this would be down to about at the rail, so two diesels would be needed to match a King. No. 18000 was of A1A-A1A wheel arrangement and its gas turbine was rated at . It had a maximum speed of and weighed . It was painted in BR black livery, with a silver stripe around the middle of the body and silver numbers. Technical details Gas turbine The gas turbine was a Brown Boveri industrial machine. It was of a type which would now be called a turboshaft engine but differed from modern free-turbine turboshaft engines in having only one turbine to drive both the compressor and the output shaft. The emphasis was on fuel economy so it had a heat exchanger (to recover waste heat from the exhaust) and was designed to run on cheap heavy fuel oil (it was also able to burn light oil but this was intended only for startup purposes). This was the same fuel that was used in oil-fired steam locomotives. After leaving the heat exchanger, the pre-heated air entered a large, vertical, combustion chamber where the fuel was injected and burned. Auxiliary diesel engine There was also an auxiliary diesel engine which provided power for starting the gas turbine. The diesel engine was capable of moving the locomotive at a slow speed when the gas turbine was not running. The usual procedure was to run the locomotive from the shed to Paddington station using the diesel engine and to start the gas turbine only a few minutes before the train was due to leave. This saved fuel and minimised annoyance from noise and exhaust fumes. Problems It proved a troublesome machine in