The Sutton and Mole Valley lines were constructed between 1847 and 1868 by the London, Brighton and South Coast Railway, the London and South Western Railway and the LBSCR-sponsored Horsham, Dorking and Leatherhead Railway.

Horsham railway station serves the town of Horsham in West Sussex, England. It is 37 miles 56 chains (60.7 km) down the line from London Bridge, measured via Redhill, on the Arun Valley Line and the Sutton & Mole Valley Lines, and train services are provided by Southern and Thameslink. Services on the Sutton & Mole Valley Line from London Victoria via Dorking terminate here, as do Thameslink services from Peterborough via London Bridge. The other services continue into the Arun Valley: a half-hourly service from London Victoria to Bognor Regis, and hourly services to Southampton Central or Portsmouth & Southsea. These trains usually divide here with the front (Southampton/Portsmouth) portion travelling fast and the rear half providing stopping services.