Police are appealing for information after a teenager was sexually assaulted in Wandsworth Common station.

The attack, which police described as "serious", took place on July 8 just before midday in the ladies toilets on the southern-bound platform.

The victim was talking to a male friend on the station's platform when the attacker grabbed her bag and ran into the toilet - she followed him but was assaulted as soon as she walked into the room.

The man then travelled on the same train to Clapham Junction, where he tried to follow the victim in the direction of Gatwick Airport.

Detective Sergeant Danny Stockdale said: "Serious assaults such as this are rare on the rail network and this was clearly a very frightening and upsetting ordeal for the victim who has been left badly shaken and traumatised by what took place."

If you were in the station or on the platform at the time call British Transport Police on 0800 40 50 40, quoting reference B13/LSA of 16/11/11, or call Crimestoppers on 0800 555 111.