Moving the ‘Jungle’ camp in Calais to UK soil in the event of the UK leaving the EU would simply encourage more migrants to attempt to reach Britain by any means and could lead to a "free-for-all", the FTA has warned.

Speaking after a warning from French economy minister Emmanuel Macron last week that a Brexit would bring an end to the juxtaposed border controls set up under the Treaty of Le Touquet in 2003, FTA deputy MD James Hookham said: “It’s one of our red-line issues, to keep the juxtaposed controls in place.

“At the moment, trucks go through British immigration controls in French territory so any immigrants found will be removed onto French soil and remain in France. Should that revert to where we were conventionally, they would land in Britain and become the responsibility of the British government,” he said. “If that arises, it would be a free-for-all among migrants.”

Whether such a relocation would really be forced by a Brexit is not clear. A statement last month to this effect by prime minister David Cameron drew fire as a scaremongering tactic within the ongoing EU referendum debate; the Home Office, meanwhile, has so far declined to comment on the implications of a Brexit for the juxtaposed border arrangement.

RHA policy director Jack Semple said it would prefer to avoid speculating on what might happen in the event of a Brexit but added: “The core issue is that migrants are desperate to get to the UK and as long as that is the case, they will see lorries as their best chance of getting here.”

Despite the unrest sparked earlier this week by the partial removal of the ‘Jungle’ camp, both the FTA and RHA continue to support the move, the RHA labelling it “a positive first step… to get the crossings back to normal” and the FTA repeating previous calls for the camp to be moved “away from the motorway and Eurotunnel facility”.