The Somerset and Dorset Railway was originally founded from an amalgamation of the interests of the Somerset Railway (commenced 1854) with the Dorset Railway (commenced 1860) from 1862. In 1875, following financial problems, the lines were leased jointly to the Midland Railway and the London & South Western Railway, to become the Somerset & Dorset Joint Railway Company. The company remained a separate, jointly managed enterprise following the major amalgamations in 1923 (between the London Midland and Scottish Railway and the Southern Railway) and nationalisation in 1948 (between the London Midland Region and the Southern Region). The company was finally closed by British Railways in 1966.