Class D3/6 were diesel shunters built in 1935 by English Electric for the London, Midland and Scottish Railway. They were the first of a new design of diesel shunters based on the English Electric 6K of 350 hp diesel engine. One demonstrator and ten production locomotives were built, numbered 7079 and 7069-7078 by the LMS. Three of these later became British Rail numbers 12000–12002 (previously 7074/76/79 respectively). The remainder were sold to the British War Department in 1940 and were shipped to France during World War II. Of these the first production locomotive, no. 7069, survived the war and was used in industrial service in France. It was later repatriated for preservation and is now based at the Gloucestershire Warwickshire Railway.