These coaches were built for the Southern Railway by the Birmingham Railway Carriage & Wagon Company and delivered between December 1947 and May 1948. They were made up into ten three car sets, numbered 795 to 804 and referred to as ‘Type M’ or ‘Cross Country’ sets. The formation was two of these brakes with a corridor composite to D2320 (Comet Models S17K) between them, with the first class end adjacent to the even numbered brake coach.
The sets first saw service on the South Western section but were all moved to the South Eastern section by September 1948. In 1954 the first eight sets went to the Oxted, East Grinstead, Tunbridge Wells lines, the other two sets being separated then combined with other coaches in 1957 to form sets 473 and 474.