Oh dear - I didn't think I was changing the subject; nor was I trying to have a discussion about EU issues etc. I was simply trying to point out (because Shengen had been mentioned in the context of this thread, and you're referred to the argments of the last four years) that the arguments over EU membership in recent years weren't primarily about Shengen - hence the problems (for things like international sleeper trains) of the UK not being inside Shengen were unlikely to be much different whether with the UK inside or outside the EU.
In other words, it's the border check problem, rather than EU membership per se, which seems to make it difficult to have sleeper trains under the Channel. Of course it's possible to be outside the EU but within Shengen. (Not that that's a political runner here.)