Joshua Gardner smashed the car’s window and attempted to repeatedly stab the driver

A teenager who was spared a jail term after attacking a motorist with a “zombie” knife has been imprisoned after appeal judges ruled that the original sentence was too soft.

Joshua Gardner, 19, was given three and a half years after one of the government’s senior law officers personally appeared at the Court of Appeal to argue that the first sentence was “unduly lenient”.

Gardner was originally sentenced to two years at his trial in November at the Old Bailey, but the judge then suspended that term for the whole tariff.

Increasing the sentence, Sir Brian Leveson, the senior judge on the appeal bench, described knife crime as “one of the great problems our society is facing”.

Gardner, who was 17 at the time of