It is called “the great train crash”. The European Union’s negotiations with Turkey are coming to the crunch. In December 1999 Europe’s leaders agreed, after a few minutes’ debate, that Turkey would be a candidate member. Its accession would not be a matter of if, but of when. Now a number of leaders, perhaps a majority, are trying to wriggle off the hook.

Would Turkey’s accession be a good thing? For Turkey it would probably be the best thing that could happen to it, even though enthusiasm for membership there is waning. For the EU it would be a bad thing. Why?