The posters strung across the street in Montreuil, east of Paris, were still fluttering in the breeze days after the stage, the microphones and the politicians at the launch of France’s newest political force had gone. Here, out of the smouldering ashes of the country’s bickering left, a coalition had risen to take on the far right. The Nouveau Front Populaire (New Popular Front; NFP) is a tetchy alliance of Socialists (PS), Greens (EELV), Communists (PCF), hard left Insoumises (Unbowed; LFI), and other red-banner candidates that polls suggest is the country’s best – if not only – hope of staving...