Interviewed in the Guardian, outgoing Metropolitan Police commissioner Sir John Stevens warns that London's growing knife culture is becoming one of the capital's worst crime problems.

He said the growing fashion for carrying knives was "extremely worrying" and that police must tackle it head-on.

"The key to this is our neighbourhood policing teams," he said.

"It's not quite Dixon of Dock Green, but it's certainly more akin to the type of policing I remember when I started on the beat in 1962."