 At the time Parliament was hostile to permitting closely parallel construction, and it became clear that the only way forward was to combine to build and use a shared line as far as Paisley.The Acts for the two schemes received the Royal Assent 15 July 1837, and the new companies were called the Glasgow, Paisley and Greenock Railway (GP&GR) and the Glasgow, Paisley, Kilmarnock and Ayr Railway (GPK&AR).The GPK&AR opened a section at its southern end on 19 July 1839 between Irvine and Ayr (Newton-on-Ayr), and it started operation on the Joint Line on 14 July 1840 from a temporary station at Glasgow (Bridge Street) to Paisley.