For fun, I tried out different combos from Toulouse/Marseilles to YYZ/YUL/YVR and on different dates. All have a base fare of 1€.
Even after being a FF for almost 20 years, I still can't tell, in good conscience whether this fare is real or a mistake. I have seen plenty of ex-EU fare at 1€, this is nothing new but they were all for intra-Europe flights. I have not seen a translatlantic flight at 1€ however, not even on Easyjet or Ryanair. Oh wait, they don't fly to Canada, my bad. Perhaps BA is trying to become Ryanair of transatlantic, given their repeated errors and abysmal customer service, that wouldn't be a surprise.
I happen to need a flight out of Toulouse given that there are friends I promise to visit this year in south-west France in the pays d'Oc that I have not done so yet. But seeing the way BA constantly cries wolf lately, I am going to play one of those villagers and consider this is another cry wolf incident and BA is the farm boy that deserves to be eaten by the wolves.