The T Stock was a series of electric trains originally built in various batches by Metropolitan-Vickers and the Birmingham Railway Carriage and Wagon Company for the Metropolitan Railway in 1927–31 for use on electric services from Baker Street and the City to Watford and Rickmansworth, though rarely some worked on the Uxbridge branch.

The earlier batches were built from wood and sandwiched trailers of 1898–1923 vintage, however later batches were steel in construction and worked with new built trailers. As built the group has some variations in equipment, mostly to allow use with existing stock such as the Saloon and Ashbury trailers and leading to incompatibilities within the class, however upon transfer the London Transport this was rectified and the entire fleet largely standardized about 1938.