The Mechanical Horse was conceived following a request from LNER to the quality car and aero-engine makers Napier. Not wishing to manufacture the concept, they in turn sold the idea to Scammell of Watford, whose designer O D North refined and developed the idea, which was launched in 1934. The early version was constructed on a steel channel frame with a cab made of wood with canvas doors. It came in two sizes, capable of carrying loads of 3 tons and 6 tons and was powered by a Scammell side valve engine. With a road speed of around 20 m ph, petrol consumption was between 10 and 20 mpg. Over the years the Mechanical Horse was updated in design, materials and engine capacity and lasted in production until 1967.