Who is this man?

British Transport Police (BTP) officers want to speak to him after a group of teenagers were threatened with a knife.

The incident happened on a Liverpool Street to Southend Victoria train as it travelled between Wickford and Hockley at 1.50am on Saturday, 15 August.

PC Lauren Newling said: “A man on the train got involved in an altercation with a group of teenage boys.

“A fight broke out and other passengers stepped in to stop the violence.”

The older man got off the train, but the two groups continued to argue and the man got back on.

He produced a knife and chased the teenagers through the train, before leaving at Hockley station.

Officers now want to speak to anyone who witnessed the incident or has information about what took place.

PC Newling said: “Thankfully this sort of incident is rare, and in this case nobody was seriously injured.

“However, this was a violent incident which frightened other passengers.

“I think the man in the image we are issuing today has information which could prove particularly useful to our investigation.

“Please let us know who he is.”

Anyone with information is asked to contact British Transport Police on 0800 40 50 40, or text 61016, quoting reference ESUB/B3 of 12/10/2015. Information can also be passed anonymously to the independent charity Crimestoppers on 0800 555 111.