The Somerset and Dorset Joint Railway (S&DJR) 7F 2-8-0 is a class of steam locomotive designed for hauling heavy coal and goods trains. Eleven were built in two batches in 1914 and 1925 and were used until withdrawal between 1959 and 1964.

The Midland Railway, joint owners of the S&DJR with the London and South Western Railway, were in charge of locomotive policy on the line. The S&DJR was heavily graded and required power over and above what was available from the Midland's small engines. M. H. Ryan, S&DJR locomotive superintendent argued for a type specific to the line. Two plans for 0-8-0s were suggested in 1907 but would have been too heavy.

James Clayton the draughtsman at Derby was given a free hand to design the engine and produced something unlike any other Derby-designed locomotive of the time. The design used the G9AS boiler from the Midland Compounds, with a Belpaire firebox and Walschaerts valve gear. A leading pony truck was added, to distribute the weight, making it a 2-8-0. The cylinders were mounted high on the frame, and sloped, to avoid fouling platforms.

The S&DJR locos were taken into LMS stock in 1930 and renumbered 9670–9680. They were renumbered as 13800–13810 in 1932. On nationalisation in 1948 BR added 40000 to their numbers making them 53800–53810.  Withdrawals of the locomotives occurred between 1959 and 1964.

Two are preserved.