An 18-year-old man was assaulted in Northampton’s Market Square.
The victim was leaving the Halifax bank at about 4.20pm on Wednesday, May 10, when it is alleged he was approached by a man who punched him once in the face.
The offender then walked off in the direction of Moon on the Square.
He is described as white, and he wore a red baseball cap, a grey t-shirt and a jumper tied around his waist.
Witnesses or anyone with information are asked to contact police on 101 or Crimestoppers anonymously on 0800 111 555.