There is a comforting cliche in Brussels that the European Union (EU) needs crises in order to progress. But the current cocktail of problems facing Europe — refugees, the euro and the danger that Britain might leave the union — look far more likely to overwhelm the EU than to strengthen it.

For the first time in decades, some of the fundamental achievements and tenets of the EU are under threat. These include the single currency, open borders, free movement of labour and the notion that membership is forever.

Rather than rising to these challenges, the EU is creaking under the strain. Its 28 members are arguing bitterly and seem incapable of framing effective responses to their common problems.

These arguments are also taking place against an ominous backdrop. Large parts of the EU remain sunk in a semi-depression with high unemployment and unsustainable public finances. The problems of an imploding Middle East are crowding in on Europe, in the form of hundreds of thousands of refugees. And the political fringes are on the rise — with the latest evidence being the election of a far-left eurosceptic candidate to lead Britain’s Labour Party.

With a sense of crisis mounting and the EU unable to respond, countries will be increasingly inclined to act unilaterally or even — in the case of Britain — leave the bloc altogether.

The refugee crisis is already threatening cherished ideas about open borders. In the past couple of days, Germany has reimposed frontier controls with Austria — which, in turn, has imposed controls at its border with Hungary, which itself is working feverishly to complete a barbed-wire fence to protect its frontier with non-EU Serbia. Controls have been tightened on the French-Italian borders, while migrants camp miserably in Calais, hoping to cross to England.

If the EU somehow gets a grip on the migrant crisis, these measures may be no more than temporary expedients. But if the pressure of would-be refugees heading for Europe remains intense, then temporary measures could harden into permanent controls.

Question marks over open borders will easily shade into wider issues about access to welfare systems and labour markets. That is because EU countries are realising that — in a border-free single market — a unilateral change of asylum rules by Germany had implications for the immigration policies of all member states. Once migrants get citizenship in one EU country, they have the right to move to any other, to work there and to claim benefits. But if free movement of people and labour come into question, so does the EU’s single market — its central achievement.

The refugee issue has, for the moment, overshadowed the euro. But the problems of the single currency have not gone away. On the contrary, Greece’s decision this summer to knuckle under and accept yet another austerity package has made the Eurozone look increasingly like a trap.

Even Greece, which is profoundly unhappy with life in the Eurozone, cannot risk leaving for fear of provoking a financial and economic crisis. Creditor countries such as Germany and the Netherlands are not much happier, as they fear they are being dragged into a system of permanent fiscal transfers towards the nations of southern Europe. Meanwhile, efforts to make the euro work better, by pressing ahead with a banking union, are stuck in Brussels. This does not look like a sustainable situation and the risk of euro break-up will surely return.

The refugee and euro crises bear on whether Britain will vote to stay in the EU, when it holds a referendum in 2016 or 2017. Until recently, the opinion polls looked promising for the pro-EU camp. But the migrant crisis plays directly into the most potent issue deployed by those campaigning for Britain to leave — which is that membership of the EU means that the United Kingdom cannot control immigration. More broadly, the British are less likely to stay inside an organisation that seems to be failing. If they vote to leave, the sense of crisis within the EU would then mount — raising the possibility of further defections.

A partial unravelling and marginalisation of the EU still looks more likely than a full-scale collapse. But even if an organisation called the EU continues to exist — running buildings and paying salaries — it risks becoming increasingly irrelevant.

The best way to avoid these sorry fates would be for the bloc to demonstrate its relevance and effectiveness - by showing EU citizens that collective action and co-operation are the only ways of dealing with issues like the migrant crisis.

The trouble is that the EU’s complex and unwieldy decision-making processes make it extremely hard to respond quickly and coherently to a crisis — as the migrant issue illustrates.

For people of my generation, one of the central political themes of the past 40 years has been the steady advance of the European project. It is hard (and alarming) to imagine all that going into reverse. But Europe’s turbulent history is littered with examples of empires, monarchies and alliances that rose to greatness and then collapsed. The organisation that the EU sometimes reminds me of at the moment is the League of Nations — a high-minded body, committed to international cooperation and the rule of law — that was eventually swept aside by international events that it could not cope with.

— Financial Times