Is it a bird? Is it a plane? No, it's Boris!

Mayor of London Boris Johnson has been hailed a “knight on a shining bicycle” by a woman whose aid he came to as she was being attacked by a gang of girls armed with an iron bar.

The incident took place in Camden, North London, on Monday evening as film-maker Franny Armstrong, the director of The Age of Stupid and a climate change campaigner, walked home.

Ms Armstrong told BBC news that she had been texting on her phone when she was pushed against a car by the girls, one of whom was brandishing an iron bar. She called out to a passing cyclist for help, little suspecting that she was giving the mayor a golden opportunity to personally put his policy of tackling youth crime into force.

The mayor stopped, asked the girls, “what do you think you’re doing?” and then, when they ran off down the street, picked up the iron bar and tore after them on his bike, calling them “oiks,” before returning and insisting on walking the film-maker home.

Ms Armstrong admitted that she wasn’t a fan of the mayor’s policies and had voted for Ken Livingstone in last year’s mayoral election, but said: "If you find yourself down a dark alleyway and in trouble I think Boris would be of more use than Ken."

The mayor’s office was reported to have confirmed that the incident had taken place, but said that the mayor had no further comment on the incident – very much in keeping with the modest nature of mild-mannered superheroes everywhere.