If the Government is serious about maintaining its pretence of leaving the EU with no trade deal, it will have to pave paradise and put up a parking lot.

Just off the M20 at Folkestone, 10 miles out from the port of Dover, there is a smallish lorry park with 82 spaces. Almost unseen behind the KFC and the WHSmith, Turkish truckers wash their underwear in coin-operated laundry machines.

It’s privately run, and serves a niche market. It provides customs clearance for lorries driven to the UK from outside the EU. Such clearance is not completely straightforward, and if the UK leaves the EU with no deal, it is estimated a thousand or more such parking spaces will be required.

Dover is the world’s busiest port for freight lorries, but for understandable reasons, less than 1 per cent of its arrivals have driven all the way across the European Union to get here. The vast majority of this 1 per cent have come from Turkey or Switzerland. The customs requirements made of them are not straightforward, and if hard Brexit occurs, these are requirements that are likely to require replication for the other 99 per cent. The risks are huge.

It is a bewildering proposition. Brexiteers both in and out of government like to repeat the claim that processing these lorries takes “20 seconds”, but any of the drivers who stop here for lengthy periods will tell you a different story.

"First you are driving in, then parking, then taking a form to be signed. It's not 20 seconds, it is long time," says Ahmet, a 44-year-old Turkish driver who regularly calls in here on long drives between Turkey and the UK.

Twenty seconds is the time it takes the computer to check the documents, which are actually approved by a customs centre in Manchester. They earmark the taxes that must be paid on the goods and send it on its way. It does not include the time spent parking up and bringing the documents to the desk.

Most significantly, it does not include the 35 minutes lorries are routinely made to wait to satisfy EU rules on the transit of goods.

When the Turkish delight and Swiss chocolates arrive in the UK, they are subject to certain duties. But France, Germany and everywhere in between need to know that none have fallen off the back of the lorry en route, and avoided duties there.

Once out of the EU, it has been claimed, the UK will be free to ignore these EU directives, but it is not that simple. If the UK retreats on to WTO rules, taxes will have to be collected on absolutely everything that arrives, from every country. Currently the facilities simply do not exist to do this.

In nearby Stanford, there has been talk of building a huge lorry park to end “Operation Stack”. That is the procedure that turns the M20 in to a temporary lorry park when relatively rare problems at Dover cause miles and miles of queues. In theory, that lorry park could also be used for customs checks, but approval for its construction was granted two years ago, and work has not begun. It involves covering wide acres of green pasture in wide acres of tarmac. Unsurprisingly, local residents are furious. A local campaign against it is making glacial progress through the court system, with residents ruling out an out-of-court agreement. The time for further delays is rapidly running out.

The consequences of delays at Dover are fatal. Recent estimates suggest even two minutes per lorry would create 17-mile tailbacks. Dover’s MP Charlie Elphicke, who has been undertaking exhaustive research into finding a solution to the problem, says significant delays would leave the “Northern Powerhouse powered down, the Midlands Engine switched of..” Parts for virtually all cars made in the UK come through Dover. Delays have knock-on effects for productions lines everywhere, and those knock-on effects would come fast.

Factories hold inventory for a matter of hours, knowing the next load is on the way up the motorway from Dover. Having to be resilient to potential delay involves holding vast amounts of extra stock. Privately, government advisers says it makes the UK a “risky place to do business”. If no clarity emerges on the situation by "very early next year", manufacturers will have to strongly consider moving operations to within the borders of the European Union.

Effectively, the country must start to make extensive preparations for an outcome it doesn't want and that may never happen. Customs officials admit in private that hiring processes would need to "start now", without any real idea of the needs that will ultimately be required.

The customs checks are carried out by small, private companies, who only call in an HMRC inspector as a matter or last resort. Technological changes, and massive simplifications that came into effect in 1993, mean very few such companies remain. Of those that do, there is little evidence that they even want the vast amounts of business that could come their way. Margins are already extremely tight. If they are overwhelmed, prices will be driven down, requiring either the Government itself, or a huge, DHL-type operator to step in.

The Institute for Government estimate that up to 5,000 more staff will be needed. And if these staff are to be trained and ready for work on 1 April 2019, the recruitment process will need to begin early in the new year at the latest. And they would have to recruit for jobs that, in the event of a deal or even a transitional arrangement, may never need to be filled. Customs officials describe Brexit as “impossible to plan for”.

“What we should be doing now is investing in world-class systems,” Mr Elphicke said. “Systems that you can get in place that do it on fast turnaround.”