The Bridge of Weir Railway was an independent railway company that built a line from Johnstone to Bridge of Weir. It was taken over by the Glasgow and South Western Railway (G&SWR) in 1865 and formed the base of a line that extended to Greenock, giving the G&SWR access to the harbour facilities there, competing with the rival Caledonian Railway. The Greenock branch, as it had become, was given a direct access from Elderslie (about midway between Paisley and Johnstone), and fast passenger trains ran between Glasgow and Greenock.