A group of men hurled homophobic abuse at women on a train between Blackpool North and Preston.
British Transport Police say the men were abusive and violent, sprayed a bottle of shaken-up lemonade at them and knocked a 21-year-old woman to the floor and assaulted her.
She suffered bruising and swelling to her face, head and arms and has suffered from partial memory loss since the incident.
Police today released a CCTV image of a man they would like to speak to in connection with the incident, which happened at around 11.15pm on March 29.
PC Tony Greenwood said: “This was a particularly nasty and vicious assault which all began with unwarranted and totally unacceptable homophobic abuse.
“Sadly some people seem intent on causing trouble and we will use all tools at our disposal to bring them to justice.”