A rail worker needed stitches to his forehead after being punched in the face as he intervened to stop a brawl.
The fight broke out at Camden Town Underground station just after midnight on February 22.
A member of staff intervened to break up the fight, and as he did so was punched in the face, British Transport Police said.
He attended hospital and received stitches to an open cut on his forehead.
Officers have now released CCTV images of a man they would like to speak to.
They believe this man has information that may assist the investigation.
Anyone with information should contact BTP by texting 61016 or calling 0800 40 50 40 quoting reference 11 of 22 February.
Alternatively, you can contact Crimestoppers anonymously on 0800 555 111.
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