For the second time in four races, grand prix organisers are on red alert against the possibility of political disruption of their event.
Although the situation in Montreal is nothing like as serious as it was in Bahrain, where violent riots began in March 2011, the traditional open-doors walk-in day has been cancelled here today at the Circuit Gilles Villeneuve a few miles outside the city. Angry students have threatened to do everything they can to upset the running of the race as a protest against increases in their annual tuition fees.
In past years, fans could walk down the F1 pitlane on a Thursday, but that facility has now been withdrawn.
François Dumontier, president of the Canadian Grand Prix, said: "Cancelling the day was the only action we could take. Sadly for the fans, it was impossible to escape from such responsibility."