A woman was pushed and spat on by a couple whom she asked to stop having sex on the tube, British Transport Police said.
The victim spotted the couple’s night tube romp on January 14 at 1am, as the train passed through Kennington on the Northern Line.
As she approached the brazen couple to demand they stop, the man got up and began his attack on the victim.
PC Suleman Yazdani, who is leading an investigation, said: “This is highly inappropriate behaviour, the woman was simply asking this couple to stop, there was no need for aggression.
“If you were on that train or saw anybody acting suspiciously I would urge you to contact us as soon as possible. Any information, no matter how small, could be vital to our investigation.”
Anyone with any information can contact BTP by sending a text to 61016 or calling 0800 40 50 40 quoting reference 13 of 14/01/2017. Or contact Crimestoppers anonymously on 0800 555 111.