Built between 1962 and 1968, the Class 47 Co-Co Diesel-Electric locomotive was once the most numerous class of mainline diesel in Britain with 512 examples. 310 locomotives were constructed by Brush in Loughborough, and the remaining 202 at Crewe. The locomotives were used for passenger and freight operations. Between 1998 and 2004 33 of the locomotives were converted to Class 57s by Brush Traction. The Class 57 features re-conditioned EMD engines and new traction alternators. GWR operate a small fleet of Class 57 locomotives primarily to haul their Night Riviera services in addition to the occasional stock movements and special trains. Each locomotive is named after a castle found in either Devon or Cornwall.