Police are still hunting for teenagers who “ran off laughing” after viciously attacking a father walking down the street with his son in Mitcham.

The victim, a 47-year-old man described by police as “vulnerable”, was first treated for a minor head injury sustained in the attack. However a few days later scans showed he had suffered internal bleeding around the brain, and he was called back for further treatment. He has now recovered.

Police said the victim was walking along Armfield Crescent, near the junction with St Mark’s Road, with his 12-year-old son when he was assaulted on September 21 last year.

A police spokesman said: “Two youths came up to them, one of whom punched the father without any warning, knocking him to the ground. The youths then ran off, laughing.” The attackers were described as black teenagers, aged about 16.

Anyone with information should call Crimestoppers on 0800 555 111.