A total of thirty Class 67 locomotives were built between 1999 and 2000 by Alstom, in Spain, for English, Welsh & Scottish Railway (EWS). These Bo-Bo configured diesel electric locomotives have a large fuel capacity, electro-pneumatic brakes and a top speed of 125mph (200km/h). The bodyshell is a monocoque load bearing Alstom design, whilst the bogies, also designed by Alstom, are of an "H" frame design. The engine, traction motors and control electronics are the same as those used in the Class 66, but differ in that the traction motors are frame mounted, rather than axle hung, to reduce unsprung mass.

The gear ratios have also been increased, allowing higher speeds and the cab is designed around a central driving position. The Class 67 locomotives are able to supply electric head-end power for passenger train heating and air-conditioning and are equipped for buffer and screw coupling, as well as also coupling via a buckeye coupler, attached on a swing arm mount. Locomotive number 67014 was built in March 2000 for EWS. In 2008 the locomotive was repainted silver and grey and operated for Wrexham & Shropshire under the name ‘Thomas Telford’. The locomotive also operated Chiltern Railways services before eventually being repainted into its current Transport for Wales livery and preforming services hauling a rake of Mk4 coaches.