This is about the EU Referendum. As David Cameron pointed out the other day, it’s really important; more important than a General Election. You elect a government for 5 years and if you don’t like them you vote them out again. But a vote to leave the EU is a one-way trip; you don’t get to change your mind again however bad things get. Sure, you may be able to re-apply for membership, but not under the terms you enjoyed before you left.

I’m in favour of Britain remaining in the EU. For lots of reasons, and I’d have to write a book to explain them all. Which few would read. So I’m just going to pick the one subject that fills the news more often than anything else.

I visit pro-Brexit Facebook Groups from time to time, to see what people are really angry about. And they are angry. Incredibly so. According to most of the more vocal Brexit groups, the EU is an evil conspiracy aimed solely at Britain and supported by our own government, that expects us to work hard and pay for all those lazy Europeans to enjoy their idle lives in the sun. By comparison, Vladimir Putin is a nice, honest man, and when we free ourselves from the dead hand of Brussels we should make friends with Russia. Don’t take my word for this; go to BREXIT 2016 (one of the more moderate Groups), and see for yourself:

https://www.facebook.com/groups/366368093513940

The thing that gets people in this Group really upset is “uncontrolled immigration”, by which they mean the EU is compelling Britain to accept millions of immigrants to take our jobs and live off our benefits. Both at the same time, it would seem. To make things worse, most of these immigrants are members of ISIS and are planning to conduct unspeakable atrocities on our soil. So the solution is simple. Leave the EU then close our borders to all immigrants. We’ll continue to do business with the EU, who need us more than we need them, but we’ll gradually make lot of new friends around the world to replace the countries who have been doing us down for so long.

All this is wrong on so many levels I scarcely know where to start. The ignorance about basic economic facts is staggering, and the more extreme the lie the more it’s likely to be believed. Somebody, somewhere must be stirring up all this nonsense but the knowledge that there’s an army of uncritical listeners out there eager to believe the worst about the EU beggars belief.

So I’ll start with a couple of facts that even most ardent EU-haters can’t dispute. The first is that whether Britain is or is not a member of the EU, Calais is still just 21 miles away. Some appear to believe we’re able to float off into the Atlantic and park ourselves off the coast of the USA.

The second is that most of our trade is with Europe. Many would prefer this not to be so, but it is. OK, it’s only a little over half, but that’s the meaning of the word “most”. If this trade were to cease, life in Britain would be very, very difficult. Very hard, and the British people don’t do hardship. Unlike our continental neighbours we’ve never been invaded by a foreign army and put under subjugation.

Let’s not fall for the one about them needing us more than we need them. Germany  – and to a lesser extent Italy – are the manufacturing powerhouses of Europe, not Britain. From France and Spain come farm produce; we’d rather set up grouse moors than boring old farms. Sure, they want to sell to us, but they expect to be paid so we have to produce something in return. And if we’re not there to buy BMW cars there are plenty of other places that will. Our stores and supermarkets are awash with products and produce from Europe, and the sudden deprivation of these items would cause rioting in the streets. If you don’t believe that, read on; it’s already happened.

So what’s likely to cause such a break in the flow of goods into Britain? This is where I return to immigration.

Around the world, huge populations are on the move. From North Africa to the Middle East to Asia, people are escaping from wars or seeking a better life away from incompetent governments. These people are desperate and will go to any lengths to escape, even if it means standing shoulder to shoulder with 100 others for 2 days in a leaky boat on rough seas in winter. But though desperate they are not ignorant. Thanks to the mobile phone and the Internet it’s no longer possible to keep whole populations in the dark. Even in North Korea, where control of the population is the overriding priority for the authorities, news leaks in from the outside.

Just 21 miles from the English coast lies Calais, and just outside Calais is a migrant camp known as the Jungle, filled with people from North Africa who are dedicated to reaching Britain in spite of the French social security system offering them more than they’ll get from us. Also in Calais is the UK border post. When you drive back from France or beyond your papers are checked before you are allowed to board a ferry or get on the Shuttle. On arrival in Kent you just drive off and that’s it – no further checks.

It’s almost certain that if Britain leaves the EU the border post and its immigration checks will have to move back to England. Not even the EU-haters dispute this. But I have yet to see a fully reasoned discussion on either side that suggests what would happen next and puts it into the context of what is going on elsewhere.

When I raised this point on the above Group, the few that could refrain from four-letter abuse thought it could all be handled by private security firms. Apparently France already has one to police the miles of fencing the migrants try to overcome on a daily basis. We of course have our own dear G4S, who you may remember as the folks who were unable to provide the security at the London Olympics in 2012. So forgive me if I have some reservations about putting the nation’s border security in their hands.

But how does this actually work? The problem is that once a ship has sailed you can’t turn it round and ask the French to take people back. There are long and incredibly complex legal procedures to be invoked for this. So the checks have to be done on French soil before or at the point of boarding. Everyone has to be checked; migrants, tourists, lorry drivers and their cargo. At the moment this work is all done long before people get near the ships themselves, but the relocation of the control posts to Dover takes this extra barrier away.

The tone of the pro-Brexit debate is that of naked hatred of all things European. Our continental neighbours have picked up on this and their patience with us is starting to wear a little thin. A successful Brexit will be followed by the resignation of David Cameron and many of his supporters, most likely including George Osborne. Their replacements will be people from the Brexit side. Under such circumstances, can we guarantee continued full-scale cooperation from the French in our efforts to keep the migrants on their side of the Channel? It seems likely to me that travel across the Channel will become a risky business, as it is already for lorry drivers. Do you want to be lumped in with hundreds of migrants as you queue at the port of Calais to get on your ferry?

The Calais Jungle gets a lot of critical press here in Britain, but in fact so far we’ve had it easy. The numbers represent only a minute proportion of those already in Europe or trying to enter by any means available. Calais is a long way from Turkey and even from Italy, where many times the population of the Jungle have landed after their perilous crossings of the Mediterranean. This, plus the known difficulty of getting through the British Customs post, may be why there hasn’t been such a flood making their way up France or across from Belgium. But it’s going to get worse as the overall numbers increase. Italy and Greece can’t be expected to shoulder the burden alone, so if a solution is even possible it will only be by cooperation between the EU countries themselves.

Lack of cooperation hardens attitudes. Countries that refuse to cooperate will see actions taken against them as it is manifestly unfair to insist on “business as usual” when your trading partner is buckling under the pressure of incoming numbers. The Italian-French border at Ventimiglia will become a pressure point and the French have already come under considerable criticism for trying to prevent Tunisian refugees from crossing. It is inconceivable that the numbers in the Jungle will not steadily increase along with those everywhere else on the continent. And increase they will; there’s every expectation that the problem will explode this year.

Add Brexit into this, with its all too prevalent truculent “screw you, we’re off” attitude. The temptation to open the Italian border, shunt large numbers of migrants up to Calais then turn a blind eye to what happens next, might be too much, especially as the French electoral system is likely to see increasing influence by Marine Le Pen, who is no Anglophile and would have few scruples about setting up that particular confrontation.

As I’ve said already, the situation is currently manageable because the border post is in Calais and the numbers of migrants is manageable. But what if both these change?

The thing to remember is that no post-Brexit government can be seen to be soft on immigration that wasn’t there before Brexit. So no cross-channel ferry is going to leave the port of Calais if it’s full of migrants. But there comes a point at which their sheer numbers makes it impossible to prevent people getting into the port. I don’t know where this point is – nobody does. It depends on a number of things, not least cooperation between the countries concerned. And that will have just been strained to the limit by Brexit. It’s not difficult to envisage a situation where boats can’t get their real passengers or cargo on board because there are simply too many migrants blocking the roads and climbing/cutting the fences.

The effect is that ships don’t sail. Which is where I return to the title of this article.

Do you remember September 2000? In particular, the fuel tanker drivers’ strike? I was away on holiday when this started, and returned to Gatwick to pick up my car and return to Norfolk, only to find there wasn’t a single petrol station open and supplying fuel. When I mentioned rioting in the streets earlier in the article, this is what I was referring to. Panic buying brought the country close to chaos, then it all blew over and life returned to normal again.

But if close to half of our trade were to suddenly stop, it wouldn’t blow over and there wouldn’t be time to replace all our imports overnight with goods from elsewhere in the world. Britain would be instantly plunged into a situation not seen since the dark days of the German blockade during the Second World War. Life then was much simpler; most people lived close to where they worked and we produced most of our own food. It’s not like that any more. People who bang on about “wanting my country back” forget how much life has changed in ways they wouldn’t want to put into reverse. We are a much less forgiving people, now, having grown up with luxuries unimaginable at that time. Make no mistake, life in Britain would become very hard indeed almost overnight. The experience of September 2000 should have shown us how fragile our society really is and how easy it is to deal it a crippling blow.

Is this a risk worth taking just for a few largely imagined benefits? Is Brussels really so evil that total economic collapse is a sensible alternative? Make no mistake, it won’t be the high-profile Europhobes running the Brexit campaign who will suffer; they’ll just move out and live off their Swiss bank accounts. It’ll be us poor mugs who will be left to fight for whatever scraps are left.

Vote Remain – it’s the only safe option.