Drew Pinney, 23, went to the Cambridge Junction with his pregnant girlfriend on the evening of 17 October last year to watch a reggae concert.
Pinney and the victim, a man who was unknown to him, were seen on CCTV dancing together at the front of the crowd. At just before 10.30pm the two were seen to stop dancing and lean in to talk to each other. Pinney then punched the other man in the face, causing him to fall onto the floor.
Pinney, of Stevenson Court, Cambridge, ran out followed by his girlfriend while the victim was taken to Addenbrooke’s Hospital with a fractured skull, chipped teeth, split lip and a bleed to the brain.
In police interview Pinney claimed the victim had been groping his girlfriend.
Pinney pleaded guilty at Cambridge Crown Court to causing grievous bodily harm without intent and was sentenced to 18 months imprisonment.
PC Ash Bryce said: “This took place in a public place, at a leisure venue. The sentence handed out shows that such violence will not be tolerated and is a reminder that a solitary punch can have drastic consequences on people’s lives.
“Hopefully others can learn from this and think twice before resorting to violence.”