 The Joint Committee, which controlled the line, built a branch to Govan and later to Cessnock Dock, and then Prince's Dock.With the passing of the Railways Act 1921 (Grouping Act) the line, together with the Caledonian Railway and the Glasgow and South Western Railway, became part of the London, Midland and Scottish Railway (LMS).The line is still in heavy use today as the eastern end of the Inverclyde Line and the Ayrshire Coast Line.