It's fast becoming a serious issue... they will clearly stop at nothing to get here, so perhaps it is only inevitable that the authorities will need to reappraise the approach from a softly softly civilian one to hard line military one 
A British military intervention would be a jurisdictional nightmare and once aware the people trying to get through would exploit that. So it's a no-go.
Plus any thoughts on the occupation of Calais should read this. Sound familiar?

"Calais was regarded for many years as being an integral part of Kingdom of England, with its representatives sitting in the English Parliament. This was, however, at odds with reality. The continued English hold on Calais depended on expensively maintained fortifications, as the town lacked any natural defenses. Maintaining Calais was a costly business that was frequently tested by the forces of France and the Duchy of Burgundy, with the Franco-Burgundian border running nearby.[19] The British historian Geoffrey Elton once remarked "Calais—expensive and useless—was better lost than kept".[20]"