The British Rail Class 202 (or 6L) diesel-electric multiple units were built from 1957-58 at Eastleigh and Ashford Works.

These units were built to work the London Charing Cross to Hastings services.

Several tunnels along the route had restricted clearance, meaning that these units were built with a narrow body profile.

The line through the tunnels was reduced to single track, allowing standard loading gauge Class 411 electrical multiple units to replace the diesel units on passenger services.

One unit was subsequently reinstated to provide emergency cover, and was renumbered as 202001 to conform with the TOPS numbering system.