The Surrey Iron Railway (SIR) was a horse drawn plateway whose width approximated to a standard gauge railway that linked the former Surrey towns of Wandsworth and Croydon via Mitcham (all now suburbs of south London). It was constructed in the early years of the 19th century having been established by Act of Parliament in 1801, opening on 26 July 1803. The SIR closed in 1846. Part of the route was reopened in 1855 as the West Croydon to Wimbledon Line, part of the London, Brighton and South Coast Railway from 1856. Much of the route remains in use by Tramlink.