As with the 20HP petrol Motor Rail no. 39, this loco was built for active service in WW1. One of the 5th Batch of Simplex 40HP tractors ordered on 31st December 1917 by the War Department, it never saw active service, going straight into store at Purfleet Wharf, Essex, along with 31 sister locos. It was advertised for sale in June 1919. It may have been used on a Leeds Corporation contract to build a pipeline at Weetwood, Leeds.
By 1921 it had been sold to Leeds Corporation’s Knostrop Sewage Works. It remained here until 13/4/1981 when it was preserved by the Leeds Industrial Museum at their Armley Mills Museum.
The loco arrived on loan to the MRT from Armley Mills on 17/7/1995. In 2002, the restoration of this loco was the subject of an episode of the Channel 4 programme ”Salvage squad”. This culminated in the restored loco visiting the Cappy-Froissy-Domierre museum railway in northern France, which is very close to battlefields of WW1 where many similar locomotives operated. Following this adventure, the loco also visited the Leighton Buzzard Light Railway and the Ffestiniog railway