Citations needed on that claim. Claiming that anti-EU parties are more socially liberal than pro-EU ones seems completely ridiculous to me.What I'm trying to say is that in western Europe, those attitudes you are describing are more common among voters for pro-EU social democratic parties than among voters for anti-EU hard left parties. This is why the bubble for social democratic parties in my chart spreads farther into the upper left quadrant than the bubble for hard left parties does
Again, UK doesn't have separate social democratic and hard left parties
The UK/US doesn't have separate parties, but the types of voters bleeding over to the conservative parties are showing the same tendencies (rural, no college education, majority ethnic group) and those "populist" tendencies would seem to be much more aligned with the anti-EU viewpoints than the mainstream pro-EU ones.