Diagrams E109-E112 represented the final development of the 70′ coach and marked the beginning of the bow ended era. The GWR generally preferred to marshal its coaching stock with the corridors on the same side. Composites often flanked a restaurant car and had to have the first class ends next to it, hence these coaches were also handed with reference to the first class end as viewed from the corridor side. Although their length imposed some route restrictions they could often be seen working into branch stations and termini, as well as on the main line. They were introduced first on the Paddington-Cardiff service and became known as South Wales Stock, but were dispersed more widely as newer designs were introduced. The corresponding left-handed version was Diagram E109 (Comet W52AK).
The first two built had 7′ bogies (BW2) – state when ordering if you would like these instead of the 9′ type usually supplied.