The surprising story of steam trains on the Central line

When it opened in 1900, the deep tunnels of the Central line had to use electric trains because of the lack of ventilation for steam engines, but it’s not that widely known that they did have steam trains, used in the tunnels.
(c) TfL from the London Transport Museum collection
In its early days, when the London Underground used steam trains, they were limited to the sub-surface lines, with plenty of ventilation for the smoke to escape. Later, when the deep level tunnels were built, they u