F1920/1921 surface stock

The F stock was constructed for use on the DR by the Metropolitan Carriage Wagon and Finance Company as a part of the New Works Program, the fleet consisted of one hundred carriages, 40 Driving Motors, 12 Control Trailers and 48 Trailers. The carriages were built with manually-operated doors with the first train entering service on 23 December 1920.

The equipment was not standard and this stock could not be operated with another, these were significantly more powerful than the previous stocks with an acceleration of 2.4km (1.5 miles) per second. Initially there were operating difficulties because the benefits of the new trains had not been realised. The design of the front cabin had two oval windows which where separated by a central door, this limited the drivers view forward and was generally unergonomic.

The initial design was unwelcoming with a cold steal appearance, the seating covered in a Rexine-type material and grab-bars for standing commuters which where affixed to the floor and ceiling. To improve the design, a well known artist was commissioned who improved the upholstery of the seating providing armrests between the seats and replacing the grab-bars with handling straps. The stock came with first and third class accommodation when they were first introduced.

The control trailers were built into driving motors and the doors were converted to air-operation with a push button control for passengers between 1938 and 1940.

The stock was transferred to the Metropolitan line between 1950 and 1951, after its final rehabilitation scheme which included the provision of door-locking systems, these served the Uxbridge service and occasionally the Amersham and Watford services. The first service on the Metropolitan line was on 27 February 1951. During 1950 some four-carriage sets were used to serve the East London Line, which was a part of the Metropolitan line at this point and is a part of the London Overground network today, with the maintenance works being completed at Neasden depot.

The F stock on the Metropolitan line was withdrawn on 15 March 1963 with the introduction of the A60/62 stock, however, the F stock continued to serve the East London Line until 7 September 1963.

These trains quickly earned the nickname of dreadnoughts from their initial introduction, and tanks because of their all-steel construction and because they were constructed in factories which where used to construct tanks during the First World War.