The Hawksworth coach designs spanned the period between the war years and nationalisation. Several designs, including this one, continued to be built into BR days.
The style was distinctive and although appearing massive they were handsome coaches. The fundamental changes were in the roof profile, which was rounded down at the ends (dome-ended), the reversion to a bow-ended design and an increase in length to 64′. The coaches were slab sided with very little tumblehome.
The sleeper firsts were pressure ventilated but featured conventional roof vents. At withdrawal all four were allocated to the West Wales-Paddington sleeping car service.