Let us characterise political and social views in the EU debate as a continuous spectrum. At one end is a tolerant internationalism, coupled with a proper recognition and respect for one's geographical and ethnic origins. At the other is committed racism and bigotry, underpinned by potential violence. All the mainstream politicians stand not too far from the middle of that spectrum - or claim to. The issue is which way they are facing when they look for support. There is no doubt that Johnson is consciously facing down the spectrum, implicitly looking for support from those closer to the racist end. Farage is more or less openly soliciting such support, while disclaiming racist views on his own behalf.
At the extreme end of the spectrum stand Brevic, the Norwegian killer, and now Mair, the murderer of Jo Cox. Those using fear of invading foreigners in the EU debate should ask themselves hard questions about which end of the spectrum they are facing.