The Class 67 locomotives are a class of Bo-Bo diesel-electric locomotives that were built for the English Welsh & Scottish Railway between 1999 and 2000 by Alstom at Meinfesa in Valencia, Spain with drive components (engine, generator and traction motors) from General Motors' Electro-Motive Division. EMD's designation for this locomotive type is JT42HW-HS

The bodyshell is a monocoque load-bearing Alstom design, the bogies are an "H" frame Alstom design, the engine, traction motors and control electronics are GM-EMD products, and the same as used in the Class 66. Unlike the Class 66, the traction motors are frame mounted rather than axle hung to reduce unsprung mass and the gear ratio is increased allowing higher speeds. The cab design has a central driving position.

The locomotives are able to provide Electric Train Supply for passenger train heating and air-conditioning and are equipped for both buffers and chain couplers and buckeye couplers, the latter attached by a swing arm mount.