In the battle to leave the EU, the situation between Eire and Northern Ireland is emerging as a major fault line in the campaign. Specifically, when we leave the EU, there the land border between the newly-independent UK and the remains of the EU will also become the external border to the EU.
The implications of this are serious enough to have had the Joint Committee on European Union Affairs of the Irish Parliament in June last year express concerns about the re-imposition of border controls and customs checking, with potentially highly damaging effects on Anglo-Irish trade, with serious effects on the economies of the North and South.
This concern was amplified by Irish Prime Minister Enda Kelly and more recently in the BBC and currently in the Irish Times.
Interestingly, this latter piece, by Deputy Editor Denis Staunton, picks up on what he calls the "leave" campaign's greatest weakness - its failure to answer the question of what happens next if Britain leaves the EU and what kind of arrangement with Europe it should pursue.
Vote Leave, he notes, expects Britain to negotiate a trade deal with the EU, something it expects to be a straightforward process. "The heart of what we all want is the continuation of tariff-free trade with minimal bureaucracy", it says.
The Ukip-dominated Leave.eu campaign, Staunton adds, is even more relaxed, suggesting trade with the EU could continue on just the same terms if Britain leaves. "Given that we buy more from the EU than it buys from us, it is unlikely that the EU would seek to change this in the event of us leaving", it says.
When the government published a White Paper on the alternatives to EU membership, Leave campaigners dismissed it as a "dodgy dossier". Britain would not follow the path of Norway, Switzerland, Canada or Turkey in its post-Brexit relationship with the EU, but it would find a solution of its own, they said.
However, Staunton observes that it is an "an irrefutable fact" that in all third-party relationships with the EU, there is a direct relationship between the level of access granted to the single market and the number of EU rules any country must accept.
As a member of the EEA, Norway is more integrated into the single market than any non-EU country. "In return for such access, it must pay into the EU budget, adopt most new single market rules without being able to influence them and accept the free movement of people from the EU".
Switzerland's bilateral agreements with the EU involves similar obligations, while Canada, which has an advanced free trade agreement with the EU, has to accept EU rules when exporting to Europe but has much less access to the single market.
Says Staunton: "All of these countries, including Norway, are outside the EU customs union and, the White Paper warns, if Britain were also to be outside it, there would be a return of customs checks on the border".
Specifically, the White Paper states that, "under most of the alternatives described … the UK would be outside the EU customs union and so trade across the Border with Ireland would be subject to customs controls and rules on the origin of products".
To avoid this, the Joint Committee of the Irish Parliament recommended that, in the event of Brexit, "no external EU border is established on the island of Ireland separating North from South" – wishful thinking that is about as far from reality as it is possible to get.
With the prospect of border checks, however, there are fears there there will be customs posts on the border and huge queues as trucks wait for clearance. But this is a fantasy. It is wrong to assume that, because the UK would fall outside the Customs Union, it necessarily follows that there would have to be checks on goods crossing the border.
This perhaps harps back to the 19th Century origins of the Customs Union as the German Zollverein, as a means of removing time-consuming and costly border checks. In that case it certainly reflects the limited vision and the extraordinary lack of knowledge displayed by EU supporters.
The myopia is all the more remarkable as in 1949, eight years before the Treaty of Rome which put the Zollverein into effect for the original six members of the EEC, and organisation called the United Nations Economic Commission for Europe (UNECE) launched a scheme to remove cross-border checks of goods in transit.
This system, known as the Transports Internationaux Routiers (TIR) was so successful that it led to the negotiation of a TIR Convention which was adopted in 1959 by the UNECE Inland Transport Committee. It entered into force in 1960. It has since been updated and revised, currently standing as the 1975 Convention, as amended, forever breaking the link between customs control and border checks.
At the heart of the system is a document known as the "TIR carnet", issued to registered transport operators for each truck journey, listing the details of the consignments. These have to be kept in secure load compartments and sealed for the duration of the journeys. The specially marked vehicles are given free passage across borders, with any tariffs or other taxes becoming payable only when the final destination is reached.
Currently, thee million carnets are issued each year, equating to 10,000 trucks a day. Between them, they make 50,000 TIR border crossings daily. And the system has since 2003 been undergoing simplification and computerisation, to become the e-TIR system. As a 21st Century system, it is on its way to emerging as a fully electronic, paper-free operation.
As to Brexit, providing that the UK is prepared to re-enact the Community Customs Code and other flanking legislation to which EU recognition of the TIR system is tied, we could adopt the TIR system for Irish trans-border goods traffic.
This would allow for the worst case scenario, where no trade agreement was reached with the EU. Goods would be subject to varying tariffs and conformity inspections, but there would be absolutely no need for customs posts or border checks.
Where unloading has to be supervised and inspections have to be carried out, there is already an established system of what are known as "inland ports" or "inland clearance depots", where checks can be carried out on goods before delivery. Often, these coincide with break-bulk facilities and local distribution hubs, allowing operations to be combined.
As for the Republic of Ireland, a significant proportion of its trade is with other member states. A significant volume transits through the UK and sometimes other Member States before reaching their final destinations. For this, the EU already has a system in place known as the Community Transit System (CTS), its equivalent of TIR.
By this mechanism, goods travelling between Ireland and other EU Members States can use the system, passing though Northern Ireland, if necessary, and other parts of the UK. There will be no customs checks or physical inspections.
The UK can, of course, go further than the bare minimum provision, relying on TIR. If it joined EFTA, it could then take advantage of the Convention on a Common Transit Procedure, as amended, which initially agreed in 1987. This again allows cross-border movement without the need for border checks, bringing it into the ambit of the EU's CTS. The UK currently recognises this for shipping goods between EU member states. It is used for goods travelling through Switzerland.
Within the EU, the UK integrates the harmonised procedure into our own systems, implementing a substantial body of EU legislation. As part of the Article 50 settlement, it would also be open to the UK to re-enact this body of law, and agree to continue the harmonised system. This would have to be settled during the negotiations, but should not present any undue problems, as long as we don't seek to change anything.
Failing all that, there is the possibility of signing off a special, one-off deal. This is exactly what happened in 2004 with Cyprus to facilitate trade between the divided Greek and Turkish zones. Similar in many respects to the TIR and CTS, this could as a last resort provide a model for trade between the North and South.
All in all, therefore, the chances of a Brexit bringing chaos to Ireland, with new customs posts and border checks, is vanishingly slight. And what could be agreed for Ireland could also be applied to Scotland in the event that it became independent. There is little possibility of reactivating the modern equivalent of Hadrian's wall.
Scaremongering apart – for which the major culprit seems to be the UK Government – there is little for Ireland to fear from Brexit, in terms of any disruption to trade. The day after we leave, reporters on both sides of the border will be scratching their heads, wondering what all the fuss was about, as they find they have absolutely nothing to report.