Douglas Ferreira was built for the Preservation Society in 2005 by TMA Engineering Ltd of Birmingham. It was completed in July 2006 and since then has been the mainstay of the diesel fleet, commonly hauling four trips per day for much of the season. The lomomotive is owned by the Preservation Society and leased to the Railway Company. It is named after the first general manager of the railway under preservation.
Its design represents the development of the original Lady Wakefield concept, including subsequent developments from the Romney diesels. It has a twin cab body giving good visibility in both directions. The bogie chassis has worm boxes on each axle all coupled by shafts, providing power to all wheels.
The Perkins four-cylinder turbocharged diesel engine is more compact yet provides more power than used hitherto, and meets current and known future emissions requirements. A Linde hydraulic transmission allows the engine to be centrally located and the mechanical elements isolated behind a bulkhead to protect them from road dirt.
The direction is selected electronically and throttle/transmission speed is controlled by a single lever. The braking system has a common loco/train brake with a separate air-off/spring-on parking brake.