“A Úachtaráin, agus a chairde” – President and friends.  So began the Queen’s speech at a state banquet during her visit to Ireland little more than five years ago.  “An Elizabethan conquest through the medium of the Queen’s Irish?”, asked a single-sentence letter in the Irish Times.  It captured the spirit of one of the most successful visits that she has undertaken – and one of the most important.  It was recognised at the time as marking a high point in Anglo-Irish relations amidst a rising trend, made possible by the Belfast Agreement and the settlement in Northern Ireland.  But will Brexit make it all downhill from here?

This is not inevitable, but the challenges are real.  We have listed some of them on this site, breaking them down into three broad categories.  First, a mass of specifics arising from proximity or language or both (such as how fishing rights be allocated, in the former case, or what happens to joint projects between Irish and British universities, in the latter.  Second, a set of issues related to borders, both with mainland Britain and Northern Ireland.  And, third, the implications of Brexit for mutual prosperity, since Britain is Ireland’s largest export market within the EU, and the latter’s biggest trading partner.

But although none of these problems are insoluble, some of them are difficult – and have baleful implications.  We focus today on perhaps the most serious.  A cornerstone of Theresa May’s approach to the negotiation with the EU 27 is that no deal is better than a bad deal.  This is a point we put ourselves the week before her recent speech did the same.  None the less, trading with EU member states on WTO terms – a consequence of no deal being struck – would not come pain-free.  For example, a consequence would be our obligation to charge tariffs at WTO rates.  In most cases, these are low: a recent average was 2.3 per cent.  However, rates on agricultural products are higher.

About two-fifths of Irish agri-food exports come here.  These include about half Ireland’s beef exports, the best part of two-thirds of its cheese ones, and nine-tenths of its mushroom exports.  These sectors account for about 12 per cent of Ireland’s exports overall.  It isn’t scaremongering to conclude from these figures that no deal could be a disaster for Irish farming.  It will be claimed in response that we would be under no compulsion to charge WTO rates at all – that, instead, we could simply drop all tariffs on Irish goods.  However, there are two problems were we to seek to do so – one minor (at least in the eyes of some), one major.

The relatively minor problem is that Ireland would have no discretion to drop its own tariffs in response, since its EU membership binds it to a common position as one of 27.  This wouldn’t worry some British free traders – though to what degree Conservative MPs who support free markets would do so in this case were they to have constituent farmers on their backs is an unanswered question.  But there is a snag, which raises the major problem.  Under WTO rules, we couldn’t end agricultural tariffs for Ireland alone – or for any single country, come to that.  We would have to abolish them altogether.

And we presumably wouldn’t want to do so because tariff rates are an intrinsic part of an article of Brexiteering faith: trade deals.  Conservative free traders might be happy to scrap all tariffs tomorrow, but most also want to negotiate trade deals with other countries.  These will necessarily include agricultural products.  Far more than the ups and downs of sterling, the possibility of tariffs is the main economic question (which alert Tory MPs, such as Charlie Elphicke, are beginning to probe) raised for the Anglo-Irish relationship by Brexit.  Let us now turn to some of the emotional ones – returning, as we do so, to that royal visit to Ireland.

To many people there, it highlighted the putting of a painful mutual past behind us.  And now, just as all is well, the Brits have – as much of Ireland sees it – thrown everything up in the air by plumping for Brexit.  Like most Leavers here, some there think the consequences can be coped with.  But they are unhappy about having to deal with them.  The future of trade across the border with Northern Ireland is a particularly sore point at the moment.  The Irish Government is currently scouting for checkpoint sites.  These may turn out not be needed, but it is worth noting that Ireland’s Ministers clearly believe that customs posts would be an unavoidable part in customs checks.

But at the heart of British and Irish differences over Brexit is less practical problems than political psychology.  The preoccupation in much of Britain with self-government isn’t shared in most of Ireland; it is as bewildering to many there as Irish neutrality is to many of us.  In particular, there seems to have been a classic British-Irish misunderstanding about the Single Market.  “We genuinely believed that Britain would not want to walk away from [it],” Danny McCoy of the Irish Business and Employers Confederation said last week.  Others pinned their hopes in Britain staying in the customs union.  May’s speech last month put pay to that.

She floated the possibility of Britain becoming an associate member of the customs union – in other words, maintaining the present open border with Ireland, inter alia, at the same time as gaining the freedom to negotiate our own trade deals.  This looks like a big ask.  It is certainly another cause of Irish agitation about Brexit.  References to “frictionless” new border arrangements, made during the Prime Minister’s recent visit to Dublin, looked like making the best of a bad job.  In public, there is a tense harmony.  In private, Irish politicians are busy lobbying their EU counterparts, warning them against any action that might usher in a hard border.

A recent speech by Enda Kenny (who has his own problems at the moment) cast light on Ireland’s fears. “I am confident that the European Union will not bring us back to a border of division,” he said – thereby revealing a concern that it could do so if it takes a hard line over customs.  It is no bad thing for Britain to have a EU member neighbour lobbying other members of the 27 for a settlement helpful to us.  But it is not a role that Ireland is relishing carrying out – especially at a time when its own relationship with the EU is changing.  It is now a net contributor to EU funds rather than a net beneficiary.  The Commission is on its back over its competitive tax rates.

And now a fellow Atlanticist country, and a neighbour at that, is leaving the Union – leaving the latter more corporatist and problematic as a result.  Being an EU member is bound up with Ireland’s sense of identity, and its perception of itself as modern country.  None the less, new voices are making an argument for a soft Brexit in Ireland’s own interest – and, if necessary, “Irexit”.  Ray Bassett, a former Irish Ambassor to Canada, has made the case.  Debate has gone back and forth in the Sunday Business Post and elsewhere.  Britain will not be thanked in some quarters for thrusting this debate on Ireland either.

You may say that this is unfair reading of the consequences for the latter of the way in which the EU is developing.  And you may add that the future of farmers in Meath or Kilkenny is none of our business.  However, problems for our closest neighbour – with which we share a common travel area, whose citizens are not treated by law as foreigners, and which is our fifth biggest export market – are problems for us, even before Northern Ireland is not taken into account.  It is right that our relationship with Ireland is high on May’s list of twelve negotiating priorities.  But both countries will need help, mutual understanding and luck if any second royal visit is to be as big a hit as the first.