In January 1916, the company answered a War Department tender for military supply railways. The specification was for a gauge locomotive, with no more than 1 ton of axle load per axle, capable of hauling up to 15 tons at . The company designed a new locomotive, with outer longitudinal "bent-rail" frame, mounted on two driven axles. The 2JO petrol engine manufactured by W.H. Dorman & Co of Stafford was centre-set in the frame along with its Dixon-Abbott patent gearbox, which drove the unsprung axles through a chain-drive. At one end of the frame the operator sat facing to one side allowing him to drive equally well in either direction, and at the other end was the silencer and the water cooling radiator mounted with fan to provide transverse air flow. A large flywheel gave relatively smooth operation.