London Underground carriages thought to be a District Railway first class, but now thought likely to be a cutdown Metropolitan Railway eight-wheeler. A Jubilee Stock first class carriage was restored to carry passengers in January 2013 during the Met's 150th anniversary celebrations. The Bluebell Railway has four 1898–1900 Ashbury and Cravens carriages, and a fifth, built at Neasden, is at the London Transport Museum. The Vintage Carriages Trust has three preserved Dreadnought carriages. London Underground carriages The London Underground opened in 1863 with gas-lit wooden carriages hauled by steam locomotives. The Metropolitan and District railways both used carriages exclusively until they electrified in
Circle line (London Underground) with the other London Underground sub-surface lines: the Hammersmith & City line from Hammersmith to just before Aldgate; the Metropolitan line from Baker Street to Aldgate; and the District line from Tower Hill station to Edgware Road station. The line is electrified with a four-rail DC system: a central conductor rail is energised at and a rail outside the running rail at , giving a potential difference of . The running rails are not electrified. Much of the double track railway from the Hammersmith terminus to Westbourne Park station is on a high brick viaduct. East of Westbourne Park the