Possible changes in the wider world likely to make the international environment less benign for Ireland than in recent decades were assessed here last week. But what about the issues surrounding the most likely major change – Britain leaving the European Union?

After many centuries of semi-detachment from continental affairs, Britain joined the then EEC four decades ago. For well over half of the period since, Europe has been among the most divisive issues in British politics. It has become ever more divisive as the balance of forces move against membership.

Working in London as an analyst of European affairs for over decade from 1998, I was constantly struck by the steady and rapid decline in the number of people and organisations holding the view that Britain’s national interests were best served by EU membership.

This was most notable at the political level. On the Conservative side, no young pro-Europeans emerged to replace the aging pro-EU politicians. Tories under 50 today are all – to varying degrees and in many different ways – hostile to Europe and see their country’s future in a looser arrangement with the EU, if not entirely decoupled from it.

On the Labour side, waning interest, rather than antipathy, has come to characterises the attitude of the majority on the centre-left. Gordon Brown epitomised this. As chancellor, he was an infrequent attendee at EU finance ministers’ meetings. As prime minister, he was no more engaged. In 2007, for instance, he was the only EU27 leader not to travel to Portugal to sign the Lisbon Treaty. His successor, Ed Miliband, gives relations with Europe the same low priority. Last week, Labour voted with Tory Eurosceptics to defeat the government’s proposed stance on EU budget negotiations.

The shift in position of Britain’s political class reflects a wider increase in discomfort at the constraints of EU involvement. Support for membership has waned in business, the trade unions and across the rest of civil society. The media is mostly hostile. Public opinion mirrors elite opinion. EU-wide opinion polls show that Britons see less gain from membership than people in any of the other 26 member countries. Recently, national polls have shown for the first time that, if a referendum were held on membership now, the secessionists would win convincingly.

Detailed audit

If David Cameron recognises the risks of a premature referendum, he is not ignoring the need to be prepared to exit the EU. In July, the foreign office began a detailed audit of how powers exercised at EU level impact on British interests. This audit, due to be completed in 2014, will provide the basis for Britain’s negotiating position on the repatriation of powers from Brussels. But the rest of the bloc is very unlikely to accommodate this. Some see (selfish) gain in further isolating Britain and many more think it unworkable – in principle and in practice – for one member state to have de facto a la carte membership.

If Britain does not succeed in repatriating powers, the momentum behind withdrawal will grow. For Ireland, having Britain join Iceland, Liechtenstein and Norway in the European Economic Area would be, by far, the least disruptive option. But, because EEA members are obliged to accept single market legislation made at EU level, while having no say, this would be unacceptable to Britain.

That leaves the Swiss model. Switzerland’s relations with the EU are governed by a messy and ever-changing series of bilateral agreements. This framework is unsatisfactory for both sides but, given constraints on each party, it has been impossible to improve upon. For Ireland, having Britain move to such an arrangement (outside the European economic, political and legal multilateral order) would have very negative implications.

To limit the damage to our economic relations with Britain and the North, Ireland could also leave the EU, an option former tánaiste Michael McDowell appeared to advocate recently. By any economic and political cost/benefit calculation, that option would be even more damaging. Irish trade with the rest of the EU is much greater than that with the UK and foreign companies locate here for access to the wider EU market, not the UK.

All too often choices are limited to accepting the least bad option. That will be the choice for Ireland if and when Britain leaves the EU.