Slam-door train

The name came about because of the characteristic noise made by the passengers slamming the doors closed when the train was about to depart.

Some units had individual compartments, each with its own door and no access to any other part of the train; however, these were unpopular due to security concerns and the lack of access to toilets for longer journeys and many were later converted to standard corridor saloon design.

The term "slam-door" could also refer to locomotive-hauled railway coaches that did not have automatic doors, but this usage is less common.

Slam-door diesel multiple units became common in the 1950s when British Railways (BR) sought to modernise its network and replace steam locomotives.

These included the 4-CIG, 4-CEP and 4-VEPs; the former two being fairly similar while the latter was designed with more crowded seats and more doors to enable faster unloading and loading of passengers.

Finally, also on the Southern division, new slam-door diesel multiple units were introduced in the late 1950s, these were classified as Class 201 and similar and were affectionately named 'Thumpers' due to the distinctive noise made by the engines.

The slam-door trains have had a long and robust service life, but were gradually replaced by newer units with automatic doors.

Due to a number of high-profile accidents in the 1990s, the manually-locked slam doors were supplemented with electronic, driver- or guard-operated central locking before they were gradually phased out in favour of sliding doors through the 2000s, resulting in a sharp decline in the number of deaths per year from passengers falling from trains.