SR 4-DD

Conceived by Oliver Bulleid for the Southern Railway's commuter route from London Charing Cross to Dartford, the two 4-DD electric multiple units were the only double-deck trains to run on the main line railway network in Britain. Whilst common in continental Europe and North America, the restrictive railway loading gauge in the United Kingdom prohibits normal double-deck cars with two fully separated decks.

Preservation
Two Driving Motor Cars, 13004undefined at the Northamptonshire Ironstone Railway and 13003undefined at Kent Locomotives Ltd..