In 1846 promoters were planning to submit a Parliamentary Bill for a "Paisley, Barrhead and Hurlet Railway" and the provisional directors undertook to purchase the Paisley and Renfrew line. The offer was in effect guaranteed by the GPK&AR, and when the Paisley, Barrhead and Hurlet line failed to get authorisation, the GPK&AR intervened directly. Its purchase of the Paisley and Renfrew line was ratified on 22 July 1847. The Act of 1847 authorised the conversion of its track to standard gauge. The purchase price was £34,000.