The 57′ bow-ended design followed on from the 70′ coaches introduced in 1922 and were externally similar. When first introduced they went into premier express services, often in 6 coach sets, on trains such as The Bristolian and the Cheltenham Flyer. They were dispersed more widely as newer designs were introduced.
The right-hand van version of this diagram is available as W7K. The photos show the right hand version.