It was back to Calais this Wednesday for the French Interior Minister Bernard Cazeneuve. Over the last three weeks, the makeshift migrant camp has doubled in size to 6,000 people eager to reach the white cliffs of Dover across the Channel. Why the spike, and what to do about it? "Sovereignty over solidarity" can have knock-on effects: like in Slovenia, overwhelmed since nearby Hungary shut its border with Croatia. Food for thought as the UK sets the wheels in motion for an in-out EU referendum?