The British Rail Class 201 (or 6S) six-car diesel-electric multiple units (DEMUs) were built in 1957-1958 at Eastleigh and Ashford. They were built for use on the London-Hastings line. Several tunnels along the route had restricted clearance, meaning that these units were built with a narrow body profile. Power car (two per six-car set) Original 6S Units Departmental Units Some units were disbanded during mid 1960's to provide stock for the class206 'Tadpole' Units and to reform other 'Hasting Sets' after the Hither Green crash. Set 1002 was later reformed to its original formation in 1979, but set 1004 was reformed with only its original power cars and some trailers from sister class 202 and 203 Hasting Sets. Set 1003 was reformed only for the last few months of Hasting DEMU service after its power cars were used for spears, again with none of its original trailers. Set 2007 also suffered a reformation in 1969 but it remained as a full six coach set until withdrawal in 1986. Most units were withdrawn and scrapped following electrification of the route in 1986. However, one complete unit, no. 1001, was preserved by Hastings Diesels Ltd., which is based at St Leonards-on-Sea.