50049 Defiance entered service in December 1968 as D449 and was named Defiance on 2 May 1978. Part of the 1987 freight experiment, the locomotive was renumbered to 50149 and spent two years working china clay and heavy aggregate trains before reverting back to being numbered as 50049. Retired from service in August 1991, 50049 Defiance was preserved by The Class 50 Society (later Project Defiance), first at the West Somerset Railway and then the Severn Valley Railway, before Project Defiance merged with The Fifty Fund to form the Class 50 Alliance, to whom ownership of the locomotive passed to in November 2006.