Could you be a real-life superhero?
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.
- From the section UK