Designs for inner and outer suburban services
Operating in and out of major cities and towns, during WW2 the commuter rolling stock, quite possibly suffered more than that on long distance services. In addition to long distance Mark 1 corridor coaches, British Railways needed new stock for transporting workers in and out of the cities and towns.
Passenger carrying layout of each carriage to be suitable for the type of work it was intended to carry out. For short distance, high intensity commuter services, like those out of London, compartment stock was the choice as this could accommodate high numbers of passengers. Other compartment coaches and high density open coaches were provided with a toilet in the centre area but still no connection to other coaches within the train formation. These became known as semi-compartment or outer suburban coaches.