When you have the ECHR issuing rulings saying that (criminal) prisoners should have the right to vote, that is a sovereignty issue. Parliament hasn't given effect to the ruling so it's of limited influence, but it's still a sovereignty issue.
Personally, I'm not necessarily in favour of Britain withdrawing from the jurisdiction of the ECHR or the CoE. I do agree that its influence is limited and as long as Parliament always retains the power to decide how to give effect to rulings (including whether to give effect to them), it's not a huge deal, but I was mentioning it because a lot of people do think sovereignty has to be absolute to be real and I was just pointing out that even if the UK completely leaves the EU, there are still other treaties in effect that tie it to Europe in other ways.
My problem with the European Union is the concept of 'ever closer union'. At the moment I do believe the UK is still a sovereign nation even within the EU - but I'm not convinced that it would stay that way and so that's why I want it out. If the EU was still the common market that Britain joined, I'd be all for it. If it was guaranteed that it would stay as it is now I could even live with that - that's a personal position, I know many who are more hardline on leaving than I am and I don't want to suggest my position would satisfy most who want to leave.
Well, quite. And as long as that's the case, there is no diminution of sovereignty. There's a gap between the perception, the rhetoric and the reality.
The same applies to 'ever closer union' in the EU itself. European officials routinely cite the 'ever closer Union' theme when it's expedient to do so. Some of them may even believe it. But there's very little sign of it actually happening. If anything, ties have become looser since the Lisbon Treaty. In the practical politics of the EU, whenever there's a significant conflict between the interests of a member state (the UK included) and collective EU interests, the member state gets its way. There seems, hitherto at least, to be a nicely balanced equilibrium.
Unfortunately much of the rhetoric in the Brexit saga has been based on the assertion that 'ever closer union', rather than being just a long-term aspiration, has actually been achieved ('EU superstate', 'Fourth Reich' etc etc). Perception has trumped reality.
From what you say it appears that (unlike the Brexiteer ultras) you recognise this: but you believe that the risks of the present EU/member state equilibrium giving way are too great. Well, that's a reasonable position.
Correct - the refrain is about absolute sovereignty so no trade agreements etc.