A good samaritan was allegedly assaulted when he tried to stop a man from attacking a woman at Lincoln Central Station.
The suspect is said to have assaulted the woman in front of a crowd of onlookers at around 9.30pm on Saturday, October 12.
British Transport Police were called and arrested a 46-year-old man on suspicion of assault.
He has since been released under investigation.
One passerby was also assaulted as he tried to stop the attack.
Anyone who witnessed the incident and has not already spoken to police is being urged to contact BTP by texting 61016 or calling 0800 40 50 40 quoting reference 558 of October 12.