When central banks want to make an impact they act in concert. They have the power to pump money into the financial system almost without limit: to provide short-term liquidity to the world's banks.

It seems that the pressures on the banks as a result of Europe's sovereign debt crisis have become so severe that yesterday four of them did so: the Federal Reserve, the European Central Bank, the Swiss National Bank and the Bank of Japan gave three-month loans to the banks to make sure they could function through the rest of this year.

This is classic text-book stuff: what every student on a first-year money and banking course learns about central banking and what has happened many times over the past couple of centuries. The good news is that the banks have done what they have to do; the bad news is that the situation was so dire that they had to do it.

Pumping liquidity into the markets is a short-term fix, for it does nothing to affect the solvency of the banks or the ability of Greece to pay its debts, or indeed of the eurozone to survive in the medium term. All of this remains in the air.

Greece will default within the next few months but will stay in the eurozone for the time being; and the eurozone itself will break up in somewhere between five and 10 years' time.

Now, of course, that is only a best guess of the likely sequence and it may be quite wrong. Nevertheless, it seems to me that a drawn-out but ultimately terminal illness is more likely than sudden death.

If this is right, then all the guff that was Greece to be allowed to default, it would be the end of the euro and were that to happen it would in turn be the end of the European Union, is plain wrong. Default is one thing, the future structure and membership of the eurozone is another, and the future of the EU is something else again. It is quite right that our Government should have contingency plans for the end of the euro and indeed the end of the EU. But that does not mean the former outcome is immediate or the latter probable.

The really interesting issue is whether events can and will be controlled. The conventional wisdom at the moment is that a disorderly default by Greece would be a disaster. I am not sure that is right. It might actually be better for the country to default now, in the next few days, and get the news out of the way. There would be a great deal of picking up of pieces, including the need for support of several European banks that hold too much Greek debt. But the news would be out in the open and there is no automatic need to expel the country from the euro.

There is obviously the question of whether the fear of default would then switch to Portugal and Ireland but the situation in both countries is quite different. Ireland seems to have turned the corner, with exports doing very well indeed. Portugal's problem is slow growth rather than excessive public indebtedness. As for Spain and Italy, and indeed France, they all face longer-term problems but bank debts apart, are not directly affected by what happens in Greece. And at least everything will be in the open.

By contrast, a controlled default means many more months of confusion and deceit. There is confusion because different politicians, even within the same government, say different things: for example, does Germany want Greece to default or not? And there is deceit because they feel they have to proclaim that, for example, the major French banks are sound when they are self-evidently having trouble funding themselves.

So the central bank action yesterday has bought a little time but only that. It helps the banks directly and as a result helps protect the European economy from a financial squeeze as the banks' inability to fund themselves translates into their cutting their lending to business. Whether Europe continues with its present slow growth or does slip back into recession will turn on more general matters of confidence.

Greece will default in the next few months, the eurozone will break up in between five and 10 years' time