Two British thugs who punched a young man so hard surgeons had to remove half of his skull have escaped charges.

Steve Gator, 26, has been told the teenagers who ambushed him will not face court after British Crown Prosecution Service dropped the case.

The CPS said it did not have enough evidence to proceed but Steve's mother, Nina Gator, expressed her disbelief at the decision.

"Our boy is walking around with half a head -- what more evidence do they need?" Nina Gator told SkyNews. "I can't believe it."

Steven Gator, from Essex, Great Britain, was left seriously brain damaged following the attack as he made his way home from work on January 15.

The two thugs started screaming taunts and abuse at him about his cousin but when he confronted them he was hit so hard he fell back and smashed his head on the pavement.

Click here for the full report from SkyNews.