But why would any national government want to deliberately cede power to a centralised EU government? Why would power hungry politicians willingly reduce their ability to influence the way their countries run? Here's the clever bit: they didn't. Countries which might be broadly described as being "democratic" generally have in common a mechanism or mechanisms to prevent governments from acting in ways which are fundamentally against the wishes or best interests of their citizens. England has over centuries developed a system where the government is held to account by Members of Parliament and peers. Other countries have constitutions which limit the freedom of action of the executive.
The EU trick is to bypass all these long-held traditions. Under successive treaties, Parliament has allowed European legislation to come into force in the UK with very little scrutiny. In one way it's entirely necessary: because if every national parliament had the option of amending EU-wide legislation to fit its own interest then the law wouldn't be the same across the EU. But what it really means is that laws which would never have been passed by national parliaments get through under the European Communities Act and its equivalents. One Act allows all others.
The EU is an effective transfer of "power" from the electorate to the executive. That is why governing parties and those who aim for power are so keen on it. The EU gives them untold unchecked power, even if they do have to share it.
Do go and read the whole thing. As for me, I have seen so many good posts from Ed over the last few weeks that I am adding him to my RSS feeds: I recommend that you do the same.