The Great Western Railway purchased two diesel shunters, and ordered a further seven immediately prior to Nationalisation, which were delivered to British Rail in 1948–49. The two shunters used by the GWR were numbered 1 and 2, while a series commencing at 501 was planned for the new locomotives ordered in the 1940s. British Rail numbered 2 and the new locomotives in a series commencing at 15100.