London Underground rolling stock the 150th anniversary of the opening of the Metropolitan Railway special services ran in January 2013 using a restored 1892 "Jubilee" carriage, 1898–1900 bogie carriages, steam locomotive No. 1 and electric locomotive "Sarah Siddons". Further events are planned in 2013 for Locomotive No. 1, "Sarah Siddons" and the Jubilee carriage, including a "Steam back on the Met" scheduled for May. To celebrate the 150th anniversary of the District Railway the London Transport Museum are restoring a three-car Q Stock train to run on the District Line as special services during 2018. After the District Railway had electrified in 1907 it
Railway electrification system is provided by the running rails. On the London Underground, a top-contact third rail is beside the track, energized at DC, and a top-contact fourth rail is located centrally between the running rails at DC, which combine to provide a traction voltage of DC. The same system was used for Milan's earliest underground line, Milan Metro's line 1, whose more recent lines use an overhead catenary or a third rail. The key advantage of the four-rail system is that neither running rail carries any current. This scheme was introduced because of the problems of return currents, intended to be carried