The Alton line is a railway line in Hampshire and Surrey, England, operated by South Western Railway as a relatively long branch of the South Western Main Line.The branch leaves the main line at Pirbright Junction to the west of Brookwood station, Surrey, then turns to the southwest. The route crosses and recrosses the Surrey / Hampshire border, and serves the towns of Aldershot and Farnham before reaching its present-day terminus at Alton in East Hampshire.