A 29-year-old man from Lincoln was arrested after an assault on a train left another passenger with a fractured eye socket.
As previously reported, British Transport Police released an initial appeal earlier this month after a man in his 30s was said to have been punched in the face by another passenger.
It happened on an LNER service travelling between London Kings Cross and Newark Northgate at 11.30pm on March 22. The man later required a complicated operation.
British Transport Police have since arrested a Lincoln man on suspicion of grievous bodily harm. He was later released under police investigation while enquiries continue.
PC Steve Duck from British Transport Police previously said: “The victim was left with a very nasty injury which required a complicated operation. He still requires ongoing treatment, but thankfully his injuries are not life changing.”