This was the standard Period III brake third, with toilet inboard next to the guard’s van and long filler pipes on the roof. Like their contemporary all thirds to D1899 they were typical, or even archetypal, of the early Stanier stock with characteristic sliding ventilators with small fixed elements, toilet windows with a fall back top section, shell vents and transverse cover strips over the roof panel joints. As a general service coach they would have been seen over the whole of the LMS and BR(LMR). No layout of the period should be without one—or several!
Two batches were modified. The guard’s duckets were removed from eight coaches for the Sunny South Express working onto the Southern Railway. In 1937 a further three were fitted with pressure ventilation for the Coronation Scot.