It is a fair bet, writes Booker that few of the 52 percent of us who voted to leave the European Union imagined that what we were voting for might be bare shelves in our supermarkets, an end to the smooth arrival of the 30 percent of our food that we import from the EU (and much else), and the backing up of countless thousands of trucks as they wait, possibly for days, for customs clearance at Dover and Calais.
Yet such is the nightmare scenario being conjured up by the experts at the sharp end of all this trade, our main road haulage organisations, as they try to digest the shock of Theresa May's decision that we should drop out of both the EU's single market and the wider European Economic Area (EEA).
What they realise is that this would also, inevitably, mean the reappearance of customs controls at our borders with the EU (including Northern Ireland), as we drop out of the incredibly complex, electronically based system which ensures that the 12,000 lorry movements a day between the UK and the rest of the EU operate so smoothly that there are scarcely no delays.
The issue that so many people are failing to understand is that the moment we leave the EU we become what it calls "a third country". That is the inevitable, inescapable consequence of Brexit. It's what we leavers wanted, and it's what we're going to get. But we cannot and should not pretend that there are no consequences, and everything is going to be just as it was before.
As an EU Member State, it is all too easy, and we've forgotten what it was like before the border posts came down. Richard Burnett, chief executive of the Road Haulage Association, tells us that the trucks on which we rely currently enjoy such "seamless" access in each direction that "it's as easy to deliver from Milan to Manchester as it is from Manchester to Leeds.
"After Brexit", he adds, "that will no longer be the case". Unless we "get the process right", the system "for getting food into the country will grind to a halt". The same also applies to our exports worth billions a year, travelling in the other direction.
That did not stop last week a triumphalist tweet from Steve Baker claiming that: "trade will flow smoothly at border post-Brexit: 96% electronic clearance in seconds with no intervention", picking up from Bill Williamson, Customs Director, HMRC who said that that many customs declarations were cleared within seconds without any intervention from the customs service.
This, as anyone who has the slightest knowledge of the system will understand, applies only to outgoing produce as it leaves the UK. And outgoing clearance is not the issue. It's what happens the other side of the Channel that matters.
But while people such as Dan Hannan happily re-tweet Baker's silliness, it is clear from talking to representatives of our main haulage organisations that our politicians simply do not grasp the technical complexity of the system from which they are poised to walk away.
Yet every detail, from the licensing of drivers and vehicles to the avoidance of time-consuming border inspections, legally depends on our status as a "member state". And if there is going to be any movement of goods, we need to reach a series of agreements with the EU.
We could, of course, stay as part of the EU system by remaining in the EEA but Mrs May seems to have slammed the door on this. What the Prime Minister appears to be hoping for is that, on top of all the other issues needing to be resolved in those two years of negotiation, we can somehow arrange a special deal that will allow what she calls our "frictionless" trade to continue in the same way that it does now.
As we have pointed out, though, this simply can't happen, even if a lot of people are deluding themselves that Brexit will be seam-free. And at the heart of this is a delusion, which exists at the highest level, and is perpetrated by the likes of Peter Lilley. This is the mistaken belief that, because "the UK starts off in full conformity with EU product regulations etc.", there can be no problems about continuing to trade with EU Member States after Brexit.
The delusion is readily illustrated in respect of the export to the EU of "animals, germinal products and products of animal origin from third countries", in the recently passed Regulation (EU) 2016/429 on transmissible animal diseases and amending and repealing certain acts in the area of animal health. In Article 229 it sets out the five requirements that must be satisfied before animals and animals products can be allowed entry into the Union. These requirements will apply to the UK, post-Brexit.
Firstly, goods must come from a country officially listed as permitted to export the relevant categories; secondly they must come from establishments which are approved and listed; thirdly, they must comply with all relevant animal health requirements laid down by the Union; and fourthly they must be accompanied by animal health certificates and by other declarations and documents as required.
Finally, the consignments must be presented to a Border Inspection Post (BIP) – soon to be called Border Control Post (BCP) – where they must pass inspection. Only when the fees due are paid are the "Common Health Entry Documents" endorsed and the goods can be presented for customs clearance.
As can be seen, conformity with the regulatory standards is only one of the five clearance criteria. But it is the only one that currently has to be satisfied, while we are still in the EU. All the other hurdles are additional and only come into play once the UK assumes "third country" status.
Interestingly, last week, Booker made a reference to the export of racehorses, and this has been picked up by the Guardian and then by the Irish Independent and Irish Times. All three newspapers mention the Tripartite Agreement between France, Ireland and the UK, an agreement that has been in place, on and off since 1974, allowing movement of racehorses without veterinary certificates.
What none have noted is that, after Brexit, the UK will not be able to export horses of any nature to the territories of European Union Member States until it has been officially approved under Regulation (EU) 2016/429 (or preceding legislation). And, as Article 230 sets out, approval is by no means automatic.
And this is just one sector. While there are differences in others, in the precise nature and structure of controls, it remains the case that there will be very significant hurdles beyond mere regulatory conformity before "third country" Britain can export to EU Member States. Then, traffic flow will be anything but "frictionless".
Furthermore, there is no obvious relief. Booker tells us that Brussels will not allow us a uniquely privileged deal that, by the EU's very nature, it could not give to any of the other "third countries". This, he says, would not be a case of the EU erecting barriers against us. It is we who would be choosing to withdraw from the "frictionless" system of which we are now part.
The problem, though, is that neither the politicians, the civil servants, nor the media are engaging. Speaking to one senior analyst in the road haulage industry, he told me that the UK Government had "stopped doing customs" 25 years ago, when the barriers came down with the advent of the Single Market.
There is barely anyone in the HMRC, he said, with current experience of managing a high-volume "third country" operation which sends material to an organisation such as the EU. The last time we had to do with was in 1972, when there was only a fraction of the traffic, the EEC comprised six countries and the Single Market didn't even exist.
And while, different government departments were beginning to look at the issues involved in Brexit, the haulage industry had to deal simultaneously with many departments and their agencies. There was no sign anywhere that these bodies were talking with each other, leaving nobody with a clear overview of the problems the industry was facing.
Furthermore, he said, in the HMRC, there was no sense of "peril" – any appreciation of the potential consequences of a bodged Brexit, or one where no agreement is reached. With no-one pressing the alarm bells, there is almost a sense of unreality, a feeling of drift, only the nation is inside a barrel poised at the top of Niagara Falls.
We are risking a far greater danger here than our politicians seem to realise, Booker concludes, all because Mrs May has listened to those who tell her that we should leave not just the EU but also the EEA. Not once during last year's referendum campaign was any of this raised or imagined possible.
By the time we realise the danger, the barrel could be over the falls.