British Transport Police has released this image after the incident on board the 7.22pm service from Doncaster to Leeds on Saturday, 26 June.
Investigating officer PC Fran Hewlett said: “As the conductor made his way through the train informing passengers that the service would terminate at Wakefield instead of Leeds, one of the passengers became irate and aggressive, shouting abuse and foul language at the conductor and upsetting other passengers, including children.
“The man then followed the conductor to his cab and started banging on the door. A fellow passenger confronted the man to complain about his behaviour and the fact that he had upset a child with his actions.
“The man continued to engage in verbal altercations with other passengers, and physically pushed one man out of his way before leaving the train at Adwick.”
Officers say the man pictured could have “vital information”.
PC Hewlett added: “This was a distressing incident for everyone involved. The man’s actions and aggression upset other passengers, and the fact that he continued to act in this way knowing that he was in the company of a child makes it even worse. It is vital we find the man responsible.
“The conductor was simply doing his job and ensuring that his passengers were kept up to date with the progress of the service. Nobody should have to suffer abuse like this.”
Anyone with information should call BTP on 0800 405040, or text 61016, quoting reference PSUB/B5 of July 15.