Lady Wakefield is named after the wife of the former chairman of the Railway Company. It was designed and built at the Ravenglass workshops. Construction began in 1978 and the locomotive was commissioned in August 1980. The power unit is a Perkins diesel engine. A twin disc hydraulic transmission drives both bogies with chain-coupled wheels.
The cab is independent of the bonnet and mounted on rubber for a quiet driving position. The American-style hooded design gives good all-round vision, although the locomotive is usually run cab-first for best visibility.
The locomotive went for trials on the Romney Hythe and Dymchurch Railway in October 1980 to demonstrate that a single diesel loco could haul the 16-coach school train. The design was used as the basis for the new locos, John Southland and No. 14.