Media playback is unsupported on your device

Could you be a real-life superhero?

13 July 2013 Last updated at 01:23 BST

Two real-life 'superheroes' from Seattle are in London, offering advice on how to keep the city's streets 'clean' rather than 'mean'.

Phoenix Jones and Purple Reign, who see their work like that of special constables, are in the UK for a symposium for people with 'superpowers'.

They spoke to Newsnight's Kirsty Wark about what made them want to take action against criminal activity.

BBC © 2014 The BBC is not responsible for the content of external sites. Read more.

This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.