A total of 171 Castle Class 4-6-0 express passenger locomotives were built by the GWR between 1923 and 1950. 8 have been preserved and can be seen in museums, at railway centres and sometimes hauling steam specials on today’s national railway network. The remaining 163 engines were scrapped in the 1960s as part of the great changeover from steam to diesel and electric power by British Railways, most having run close to 2 million miles in service.