Sadiq Khan has attacked the decision not to send a teenage zombie knife attacker to jail.

Joshua Gardner was given a suspended sentence because, the judge said, he was kidnapped just weeks before.

But London's Mayor said he was shocked at the decision which risked undermining public confidence in the legal system.

Normally I'm very reluctant to criticise judges. We don't see what goes on in an individual case but I've seen the video - I've seen the action of this young man and the knife he used and I was scared watching it. > I don't understand how somebody who uses a knife that way is not in custody in prison. I think it's really important for judges to give the public confidence, I don't understand how it's possible for somebody in those circumstances to receive a suspended sentence. I'll be asking questions how this happened. SADIQ KHAN, MAYOR OF LONDON

The frightening video was filmed on a busy street in Croydon as people went about their day.

Gardner's outburst of violence was caught on dashcam footage of a vehicle travelling in the opposite direction.

A police officer recognised Gardner from a previous conviction for attempted robbery.