There were 44 vans built between 1888 and 1893. They were classed DD and the numbers were 1 to 44. Interior modifications in 1893 included the fitting of toilets. External modifications, date unknown, included end vestibule connections.
Several vans were recoded to DDMS in 1908.
In the 1910 recoding, the class letters were changed to _C__ and the vans renumbered.
Two vans built in 1888 were fitted with Vacuum Brake and Westinghouse Train Pipe only. These vans were later converted to full Westinghouse brake. Later vans were fitted with full Westinghouse brake