The suburban composite was a very useful vehicle as evidenced by the numbers built, 730 by the LMS and a further 161 by BR. Of these, 260 were to the above diagrams. These coaches were used in urban areas on local and commuter trains in formations of two to six coaches, often hauled by quick accelerating tank engines. D1921A differed in being 3″ narrower over the stepboards than D1921, and slightly lower over the roof vents. Some were motor fitted.