The Class 57 is a re-engineered locomotive, rebuilt by Brush Traction at Loughborough from redundant Class 47 locomotives. The locomotives are fitted with a refurbished EMD engine and a reconditioned alternator, improving reliability and performance. Three variants exist, one for freight and two for passenger operations. The class has its origins in 1997 when Freightliner ordered an initial six locomotives. In 2000 a prototype locomotive, number 57601, was converted with electric train heating, with a view to obtaining orders from passenger companies.