The class 03 locomotive is, one of BR's most successful smaller diesel mechanical shunters. The class, numbering 230 examples, was built by British Railways' Swindon and Doncaster works in 1957-1962 and numbered D2000-D2199 and D2370-D2399 (later 03004 to 03399). D2370 and D2371 were used as departmental locomotives and originally numbered 91 and 92 respectively.