The brother of MP Emily Thornberry chased three thugs along Upper Street for 40 minutes after they kicked a man unconscious outside his restaurant.

Ben Thornberry, 51, was working at Tenshi when he saw a man run out of a nearby bar with three men hot on his tail.

The group of men, said to be wearing Portugal football shirts, then tripped him up before launching a vicious attack, during which he was knocked out.

“Me and the chef saw what happened and ran outside,” said Ben, a waiter at the Japanese restaurant. “They were kicking him in the head, I thought he was dead.”

CCTV shows the attack taking place at 9.12pm. Ben and the head chef then ditched their duties and set off after one of the men.

“We got into a bit of a punch-up,” Ben admitted. “We followed one guy and the other two were behind following us. The guy said it was nothing to do with him but we had called the police and said we were going to follow him until they turned up.

“One of the other guys punched me and the chef grabbed him by the neck. I was really angry now and got into a boxing stance.

“It must have looked quite comical with a chef running down the street waving his arms.

“The owner was working that night and there we are coming back in about 40 minutes later. The chef had bruises and I had a nosebleed.”

Police have arrested three men over the incident.