The Castle class locomotive No. 5048 is a steam locomotive that was built by the Great Western Railway in 1929. It was one of a class of express passenger steam locomotives that were used on long-distance routes between London and the West of England, including Bristol and Plymouth. No. 5048 was named "Earl of Dunraven" and was in service until 1964, when it was retired and later preserved by the Great Western Society. Today, the locomotive is part of the National Collection and can be seen at the STEAM Museum of the Great Western Railway in Swindon, England.