Parcels coaches were considered in the electrification planning of 1908-1914. They were to reduce the parcels and correspondence load from normal suburban trains.
In 1921 the railways began building parcels coaches. By 1923 there were five in service, coded CM, numbers 1 - 5. They were used in parcels and correspondence transfer removing most of this traffic from regular suburban trains. In later years they performed duties as
Car 3CM was built new with a raised centre cupola for inspection of overhead. Correspondence aludes to the fact that the the Electrical Engineering Branch paid for the modification, if not the entire coach. This coach was available for inspection service as required.
A spare car at Jolimont Workshops was used as a coach during extra traffic or when one of the CM's required repairs. This was 156 _M__. The first mention of this car as a parcels coach dates to 1923. A plausible reason for that car being 'spare' is covered in the M swing door history.
In 1955 more CM vans were needed. These extra vans were modified from double ended swing doors cars then being withdrawn from service.
A conversion plan was considered in the mid 1960s. A proposal was made to fit the coaches with VLX style sliding doors.
Parcels coach traffic was not required from about 1988 when road trucks were used.
CM 1, 2 were Tait type clerestory roof vans.
CM 3 was built with arch roof and overhead inspection cupola.
CM 4, 5 were Tait type arch roof vans.
CM 10 - 13 were double ended swing door M cars converted for coach service.
