|Number built:||441 (63 7-car sets, 30 Mark 1, 33 Mark 2)|
|Engine:||4 LT115A traction motors per motor car (630v DC fourth rail)|
|Power:||1, 680 hp (1, 264 kW)|
|Formation:||Driving Motor (DM)+Trailer (T)+T+DM+Uncoupling Non Driving Motor (UNDM)+T+DM|
The 1972 Tube Stock was built to replace 1938 Tube Stock which was fast becoming life expired in the early 1970s. To save time the new stock was based on the 1967 Tube Stock which had just been built for the Victoria Line . Although they look very similar there are sufficient differences to mean the 1967 and 1972 fleets were not interchangeable (though surplus 1972 stock were later used to augment Victoria Line services). The 72ts comprises 4 and 3 car sets which together make a 7-car train.
The first 30 sets were known as the Mark 1, none of these remain in passenger service as built though a couple have been preserved including an ex-Northern Line 4-car set at Aldwych disused tube station for training and filming purposes . The second batch of 33 cars was the Mark 2 which has a slightly different interior and some equipment and control differences. The 72ts initially served on the Northern (Mark I) and Jubilee (Mark II) Lines though the latter were later were transferred to the Bakerloo Line where they remain in service. Thirty six sets are operated by the Bakerloo Line, the vast majority Mark IIs but with a couple of Mark Is converted to be compatible.
Due to their age the 72ts fleet in many ways is unique on London Underground, they are the only tube trains to retain some transverse seating and the last stock to be fitted with the once standard Westinghouse air brake . They are due to remain in service until the late 2020s at least and some will likely remain in service beyond that date in departmental service, with 2 motor cars already part of the new Asset Inspection Train.
|Bakerloo Line 3535 at Kensal Green|
|Bakerloo Line 3661 at Oxford Circus|
|Preserved Mark I 3530 at LT Museum Depot, Acton|
|Interior of Mark I stock at Aldwych|
|Bakerloo Line 3553 at Queens Park|
 Underground News Number 654 (June 2016) p. 344
 "Bakerloo Line Fleet Weld Repairs" <http://content.tfl.gov.uk/fpc-160708-14-bakerloo.pdf>
 Underground News Number 655 (July 2016)
 J. Graeme Bruce, The London Underground Tube Stock (Ian Allan, 1988) p. 109
 Anthony Badsey-Ellis & Mike Horne, The Aldwych Branch (Capital Transport, 2009) p. 103
 Piers Connor, The London Underground Electric Train (Crowood Press, 2015) p. 72