The lessons of 1968 have stood Cannes Film Festival organisers in good stead. That was when Nouvelle Vague (French New Wave) directors such as Jean-Luc Godard, echoing the leftist student protests sweeping the nation, brought the festival to a halt on its ninth day. The world’s premier film festival has since perfected the art of embracing politics without letting agent provocateurs scuttle the event.This year, the Cannes balancing act unfolded subliminally. Paul Laverty, best known for collaborations with English director Ken Loach, set the tone at the 79th edition’s opening day jury press conference. The Calcutta-born Scottish screenwriter, a member...