The drama of Brexit may soon be matched or eclipsed by crystallizing events in France, where the Long Slump is at last taking its political toll.

A democracy can endure deflation policies for only so long. The attrition has wasted the French centre-right and the centre-left by turns, and now threatens the Fifth Republic itself.

The maturing crisis has echoes of 1936, when the French people tired of 'deflation decrees' and turned to the once unthinkable Front Populaire, smashing what remained of the Gold Standard.

Former Gaulliste president Nicolas Sarkozy has caught the headlines this week, launching a come-back bid with a package of hard-Right policies unseen in a western European democracy in modern times.

But the uproar on the Left is just as revealing. Arnaud Montebourg, the enfant terrible of the Socialist movement, has launched his own bid for the Socialist Party with a critique of such ferocity that it bears examination.