::::::::I personally think that many if not most people in the UK are happy to see English and British etc as 'inner' and 'outer' nationalities: they can easily have two and yet still see them as the same as well. In the same way that England and the UK are both 'countries'. People can say "England is my country" and they can say "the UK is my country". So they can pick two, or one, or whatever they feel like when expressing it. But as they are mutually inclusive too, they only have to pick one to also pick the other. This explains why the data came out like it did. We can show what happened, but we can't make judgements (ie talk about "sole" nationality). 

 ::::::::But whatever you see the permutations as, surely it's clear that we can't make an interpretive summary from this data? There are too many alternative readings. I spend a long time presenting it in a way that readers can simply peruse it for themselves. What Ghmyrtle has done below (within 30 mins of me writing the above), has to be most outrageous act of gamesmanship I've ever seen on Wikipedia. It's his choice - or nothing!!