OK, OK, I know I sometimes go out on something of a limb, but this weekend’s Financial Times carries a fascinating interview with ‘reverse graffiti’ artist Paul ‘Moose’ Curtis. He creates his graffiti not by spraying dirt onto walls but by cleaning dirt away. He is frequently stopped by the police, wherever he works, but they always end up flummoxed. After all, since when has it been a crime to clean away dirt, no matter how selectively?