What would we do if, or possibly when, Britain leaves the EU? In recent months the chances of Britain actually leaving the EU have risen sharply. It would still be a big move diplomatically for Whitehall but with 56pc of British people wanting to leave the EU outright, the next few years could be increasingly fraught for Britain and the EU.
And it is not just the British becoming increasingly disillusioned with the EU, the EU are becoming noticeably less inclined to understand the British position on many issues.
Tomorrow the British will be again cold-shouldered at an EU summit. The view from the continent seems to be that the British are a pain and if they left the EU, the EU could be just fine without them.
Let's think about the latest row the Brits are having with the EU. The British want to freeze the EU budget, or at least their contribution. In contrast, the EU institutions, backed by the politicians of other EU member states, want a 5pc increase in the EU's institutions' budget.
So what the Brits are actually looking for is austerity for the EU itself. What's so wrong with this? After all isn't the EU the main cheerleader for austerity as a policy? What is good for the goose is clearly not so good for the gander.
It seems like a reasonable position to take and one in which it is supported by Germany, Finland and the Netherlands. However, while the others play politics behind closed doors, David Cameron is constantly under pressure from the Eurosceptics in the Tories to dig his heels in to satisfy public opinion.
Anyone who has ever lived in the UK knows that a referendum on British membership of the EU would be won handsomely by the No side and this is, I suspect, what Cameron wants to avoid, particularly as he is trying to win an independence referendum in the more traditionally pro-EU Scotland.
In Ireland, getting away from the influence of London was the clear driver of our EEC policy in the 1970s when London was seen as still dominating our small republic. But now that we have been freed of this insecurity, is it still clever to think that a European Union without Britain would be in our best interests?
I sense the anti-British feeling or insecurity with respect to Britain has diminished hugely in this country since the 1970s. For most people, the UK is a good neighbour. It is a neighbour with whom we share so much that it would be almost inconceivable to think of daily life without Britain, from the perspective of TV, newspapers, popular culture and sport.
For Ireland, there appears to be a tendency amongst the political classes to behave as if Britain doesn't exist at all. Despite the absolute centrality of Britain in our economic affairs, for example, one gets the impression that when senior officials from the Department of Finance look out east they see all the way directly to Holland as if the big island called Britain isn't there at all.
Yet, if we look at patterns of trade, 52pc of all our EU imports come from Britain. It is by far and away the biggest market for our biggest employing indigenous sectors, agriculture and tourism. British banks are exposed hugely in Ireland, having lent some €60bn here in the boom. It came as a surprise to many of us to hear the British Chancellor of the Exchequer state that Britain exported more to Ireland than it did to India, China, Russia and Brazil combined.
It is not just trade that binds us together; the demographic flows between the countries are extraordinary when seen in the context of two separate jurisdictions. One of the most striking legacies of this intertwining is the fact that there are more British people today with one Irish grandparent than there are Irish people with Irish grandparents. In the past few years we have seen the pattern continue. In our boom, the biggest ethnic minority in Ireland was the English. Since the crash the main destination for Irish people emigrating is still Britain, and London in particular.
So what might happen if Britain were to leave the EU? The most significant fact, which is not fully appreciated, is that the EU would suffer an enormous loss of status. There seems to be a view that the EU wouldn't suffer, but Britain would suffer a slump in prestige and position. It is not so clear this would be the case. The EU without a major country like the UK would be diminished on the world stage. It's northern European, free-trading character would also be diminished, as would its budget.
For Ireland, it would mean being part of an enterprise where of the two other countries we joined with in 1973, one isn't in the euro (Denmark) and one isn't in the EU (Britain). Far more importantly, it would mean our two major trading partners, the US and the UK, would not be in the same orbit politically and we would be tied to a project which we would be entirely unsuited to economically. Ireland would be a total outlier in terms of economic integration, while culturally we would be in a club with which we share practically nothing.
These are big issues. Understandably, we would want to row our own boat independent of London, but equally we should at least be sure which way the current is going and be sure it is bringing us in the appropriate direction.
David McWilliams' new book 'The Good Room' is out now