To go back to the question of what would happen if there was a referendum in both England and Scotland, and the English voted no and the Scottish voted yes.
We would be voting on two different questions. The Scottish would be voting on whether or not they wanted to be a separate state. If they voted yes, the English cannot force them to stay part of the UK.
The English would then be voting on if they want to be part of a new arrangement in which we are in a union with only Wales and Northern Ireland. It shouldn't be assumed that the English want to be part of that new arrangement. If the English vote no, then they have to come to a decision about what they do want, in the absence of Scotland.
To me, it would seem ridiculous for England to be part of governing Northern Ireland in the absence of Scotland. A large part of the culture, politics and family heritage of Northern Ireland is closely linked to Scotland. It would very problematic for England to be dealing with Northern Ireland without Scotland. So I would vote no to England remaining in a union with Northern Ireland if Scotland goes.
In some ways I wish they would carry out a referendum in England first, so that we could go first before Scotland does so. I resent being left with the massive ethical problems associated with governing Northern Ireland. I think Scotland should be thinking a lot more about what the impact will be on Northern Ireland if they break away from it, rather than the Scottish general public expecting England to sort it out.
Because ultimately, whatever happens in Scotland, England and Wales, there isn't a great likelihood of people killing each other just because of a bit of political change. But that remains an issue in Northern Ireland, and I think that should be the priority of both the Scottish and the English when considering their independence.