In the UK there is a certain pride in their legal traditions, but there seems to be a confusion about what it all means - the concepts of referenda and parliamentary sovereignty are increasingly uttered in the same breath, seemingly without the speakers' awareness of how much these concepts are incompatible. The UK is famous for its unwritten constitution. Of course it has a constitution, but it's not codified - and a lot of people don't seem to know what it is, exactly. And the bigger question is: is the old constitution, favoured for its flexibility, up to the task of serving today's Britain?
There are many factors to be considered in UK constitutional law, but the most famous one is the doctrine of Parliamentary Sovereignty (PS). PS basically means that parliament is all-powerful, just like god.* According to constitutional theory, if the Westminster Parliament repealed the India Independence Act 1949 tomorrow, then India would revert back to British control (who says constitutional law has to make sense? Or even be practical?).
The UK constitution is just made up of acts of parliament (so it can be changed by a simple majority vote in parliament). Parliament can do whatever it wants (except anything that restricts its ability to do whatever it wants in the future). PS also means that parliamentary Acts are superior to judge-made Common Law, which is quite sensible in a democracy. The problem is that PS rests on its recognition by... judges. Because the doctrine of PS is in itself a judge-made concept.
Confused? Well, it dates back to the Civil War and the Glorious Revolution,** the end result of which is that the King/Queen had the powers of an absolute monarch, provided that the Parliament was the only body that could exercise them. What parliament is, is the King, just divided up among several hundred people. It just happens to be the case that the lower House, the elected one, is now the most powerful part of the Parliament.
So the UK has a constitution which is at odds with the more modern idea of popular sovereignty (the idea that the people are sovereign, and delegate their power upwards), because it is based on the sovereignty of the monarch, which was essentially (though not completely) stolen by parliament. Referenda go, therefore, against constitutional theory in the UK.
The UK has only ever had one referendum: over EEC entry (referendum introduced by Labour).
Now the constitution of the UK is largely a political one: it depends on the political culture for its continued existence since it is built on custom and tradition, and because any parliament could overturn the entire constitution at a stroke with a simple majority (which, under First Past the Post, might only have the support of a third of the electorate). The political culture of the UK has changed a lot over the last century, and it is doubtful that the current constitution is suitable for the modern UK. The issue of Europe in British politics shows the gap in the current political culture from constitutional theory: that the Conservatives, (the traditionalist, constitutional-upholding party) are demanding a referendum suggests that they have lost all respect for the constitution - and yet are not putting forward recommendations for constitutional reform.
There are a number of issues that make constitutional reform more pressing; chief among these is devolution and human rights. Devolution has raised the well known question over English self-rule,*** and human rights has raised questions over how much the parliament should be able to overturn such rights at a whim - or even without meaning to under the doctrine of implied repeal.****
While there have been a few suggestions on these issues (mainly just the Conservatives demanding that only English MPs should be allowed to vote on legislation affecting only England - in my opinion this will just make the system more messy), but no serious attempt at a systemic overhaul. Until this is done, and until popular sovereignty is made part of the UK constitution, Eurosceptic demands for a referendum will ironically attack the British idea of sovereignty more than the EU does (Factortame resolves the tension between PS and the ECJ's doctrine of supremacy of Community law).
Given these issues though, and the lack of political attempts at reform, it has been left to the judiciary to deal with things the best they can. And over the last 40 years there has been a weakening of the judicial deference to parliament, and even (weak) limits being imposed on PS. The famous Factortame case (no.1), which confirmed the supremacy of EU law in the UK (by cleverly saying that EU law was supreme because the UK Parliament's European Communities Act 1972 really said it was, subject to the parliament's sovereign ability to withdraw such rights. ...Yes, I know, but it has to be done in such a way in law) and the Thoburn case (which started a trend of deeming some statutes to be "more constitutional", and therefore not subject to implied repeal) are good examples of this.
In fact, in Jackson v AG, Lord Steyn in obiter***** practically served notice on PS - stating that if parliament threatens access to the courts (etc.), then the courts could just dismiss the power of parliament to do so. The supremacy of the judiciary is a general feature of democracies (supreme courts being able to rule on laws being unconstitutional, etc), and the UK could be moving in that direction, albeit very slowly, and being moved there by the judges themselves.
If nobody discusses the pressing need for constitutional reform in the UK - in fact, the basic need for a codified constitution - then the judges will just have to do the job themselves, just as they did in the past.
This post doesn't have much direction to it, I'd admit. Sorry for that. In a way, I just felt like showing what a mess I think the UK constitution really is, and vent annoyance at some UK eurosceptics' lack of basic knowledge of how their country works, and what its sense of sovereignty is (basically the sovereignty of the rulers based on their control of a territory rather than popular sovereignty). However, I think that the UK needs a constitution in the traditional, write-it-down-somewhere, sense. The current constitution is out of touch with its people (though if you really like it, perhaps you'd say it's the other way around?) - and there needs to be a big effort to confront these challenges.
And if you think all this is messed up, just take a look at land law in Ireland and the UK!
*Depending on the religion. In some cases perhaps even more powerful than god.
**Where the King was fired and Parliament bought a new one.
*** Britain (more correctly the UK) isn't a nation-state. It's a collection of nations in one (historically very centralised) state. A bit like the old Austro-Hungarian Empire.
**** Parliament can't bind successive parliaments, so if two Acts conflict, the newest one is the right one - it "impliedly repeals" the old one. For human rights this could be a bit of a problem.
*****Obiter means that the judge is just saying it - it has no legal effect. But if other judges start agreeing with it, it could find its way into the legal orthodoxy.... [I think this part of Lord Steyn's judgment is at paragraphs 90+ - of the top of my head I'd say it's at 100-110].
[Note: the links for the cases are just to their wikipedia articles, which is definitely not academic. If you actually want to read the cases they should be in the House of Lord's website, though I'd say that they're so famous (ok, famous for court judgments) that you should be able to just google them.]