Fifty of these carriages were built at Doncaster in 1954 and all were allocated to the Eastern Region for use on outer suburban services from King’s Cross and Fenchurch Street. As they were required to work over the Widened Lines, the roof vents were spaced to “Metrogauge”, thus reducing the overall height.
Seating was three-a-side (with armrests) in the first class compartments and four-a side in third. The two end seats, being full width, squeezed in an extra first and two third seats, giving a total of 19 in first and 42 in third. Third class was reclassified to second in 1956.