The line was built by the London, Chatham and Dover Railway from their first line (the Chatham Main Line). Upon the creation of the South Eastern and Chatham Railway the original Ashford terminus was closed in 1899 and services diverted to the South Eastern Railway's Ashford station. The line was electrified in 1939 (750V DC third rail) to Maidstone East by the Southern Railway prior to World War Two. Electrification between Maidstone East and Ashford was completed in 1961 under the BR 1955 Modernisation Plan.