London Underground infrastructure Tube Programme, investigating replacing the trains for the Bakerloo and Piccadilly lines, is looking for trains with better energy conservation and regenerative braking. The Underground serves 270 stations. Fourteen Underground stations are outside Greater London, of which five (Amersham, Chalfont & Latimer, Chesham, and Chorleywood on the Metropolitan line and Epping on the Central line) are beyond the M25 London orbital motorway. The longest distance between two stations is between Chalfont & Latimer and Chesham on the Metropolitan line. The shortest distance between adjacent stations is the between Leicester Square and Covent Garden on the Piccadilly line. The station furthest
London Underground S Stock (ex-Metropolitan Railway) London Underground S Stock (ex-Metropolitan Railway) S stock is the designation given to one train of eight cars by London Underground in the 1930s. It was composed of converted trailers and experimental driving motor cars inherited from the Metropolitan Railway in 1933. In 1919, the Metropolitan Railway converted six 1904 saloon stock cars into the "Hustler train". These were the only cars of this type: two were driving motors, two were control trailers, which the Metropolitan called driving trailers, and the remaining two were trailers. In 1936, the two driving motors were converted into trailers, and all six cars were