The British Rail Class 108 diesel multiple units were built by BR Derby from 1958 to 1961, with a final production quantity of 333 vehicles. These units stayed in regular service until 1990, when they began to be withdrawn from traffic. They were replaced on regional services by the new "Sprinter" derivative units, or by "Turbo" units on services around London. The final units lasted in traffic until October 1993, although many saw further use in departmental service, as sandite or route-learner units. Good condition and lack of asbestos has ensured that many of this class have been saved for preservation. None are currently certified for use on the main line - although the Swanage Railway's set was hauled from the railway to Eastleigh and back, for overhaul - and is believed to be the first class 108 to have been seen on main lines for a very long time. Many vehicles have been preserved on heritage railways.