French perfidy.

Much stronger language is needed to describe the rottenness of the French government. This particular official, Emmanuel Macron, is a disgrace, as are his superior(s) and colleagues who approved his statement. And it was approved. Such a threat to do major damage to Britain would not have been made on his own initiative:

If Britain votes to leave the European Union in a June referendum, France will allow migrants to move to Britain by ending border controls and roll out a red carpet for bankers fleeing London, French Economy Minister Emmanuel Macron said.

"France Blackmails Britain: Stay in EU or We’ll Flood You with Migrants." Reuters, 3/3/16.

H/t: Gates of Vienna.