I think you're picking the wrong fight here a bit, third, since I'm not arguing for any kind of exceptionalism, nor am I saying that everyone who didn't vote blue two years ago must be a lovely progressive with the correct pro-refugee attitude. My point was that "Let them drown" is clearly not a majority view, which is the sort of belief I've encountered in some narcissists who believe that they are the exception.
No, let them drown is not a *literally* common attitude, I agree. However attitudes like: 'I'm pro-refugee, just not layabouts' 'these people come to our country and don't integrate into British values' 'the vietnamese were proper refugees, afghans just benefit from taxpayers money' are more common. and the most common of them is of course: 'this country needs to look after its own first' ignoring that refugees are a tiny, tiny amount relative to other countries. So in that sense, it is not inconceivable to see let them drown as being a figurative attitude.