Hundreds of commuters escaped serious injury when a train approaching Epsom station was derailed on Tuesday night.

The London Waterloo to Effingham Junction service was travelling at about 20mph when it left the rails shortly after 7.40pm.

Luckily all eight carriages remained upright and no one was believed to be hurt. South West Trains (SWT) and Network Rail immediately begun an investigation. Yesterday morning it remained unclear what had caused the derailment.

A spokesman reassured rail users, saying: "The train was entering the platform at a low speed. It was just the last set of wheels on the fourth carriage that came off the track.

"We are now doing everything we can to find out why this happened. Passengers can rest assured that their safety is paramount."

The line between London Waterloo and Dorking was closed until 8.45am yesterday, creating serious disruption during the peak morning period.

SWT replaced trains with emergency buses between Epsom and Wimbledon. Its tickets were being accepted on London buses.