The locomotives were initially numbered 27000-27006 and were painted in BR black livery. Construction took place at Gorton Works, Manchester with electrical equipment supplied by Metropolitan-Vickers. All seven were named after characters from Greek mythology in 1959–1960. They were primarily used for express passenger trains between Manchester Piccadilly and Sheffield Victoria. In 1957, the class was renumbered with the addition of an "E" prefix to the number. In the early 1960s, the class started to receive the standard BR green livery. At least one of the class, E27002, received the electric blue livery carried by the AC electric locomotives.