A summer afternoon in a French city centre, seven years ago. A man in a red shirt talks with his hands, mid-argument, while the crowd behind him drifts across the square. Fifty metres away, a riot squad in black moves up behind a shield wall, and a handful of demonstrators push a homemade barricade of tarpaulin and umbrellas across the tram tracks. Off to one side, students carry a red banner in Italian about Sicily and war, which has nothing to do with the local grievance and everything to do with the fact that these crowds have started to share a circuit.