Brexit is either going to happen, or never happen, long before an independent Catalonia becomes an issue for the EU.

Referendums are invariably divisive. Generally, they are highly undemocratic because they ask people to make a simplistic decision on complex issues that we elect and pay politicians to wrestle over. However, in this case I can’t see any other way. But a badly-devised referendum would be worse than useless. Both sides must fully agree the wording of the question and the bar for independence must be set very high to correct for the skewed nature of the issue apropos of the alternative outcomes. Get that right and it’s a good start. Then we have to trust advocates on both sides not to mislead the public. In our referendum the bar was set too low and both sides lied in their teeth to us. If you think that has has anything to do with democracy then I’m not with you.