I don’t know how to quote from a previous thread. Sue me, I’m old. But yes, you are right to say that the comment should apply to urban areas, outside the cities. However, that does not mean that they do not encounter immigrants. Northern urban communities often tend to live segregated lives, rather than not encountering anyone from an immigrant community. This problem is exacerbated by cultural differences, though I know I’m going to get in trouble for this.
The old communitarian ethos of the areas that went Conservative was centred around the chapel, the unions and the pub. Immigrants were overwhelmingly from Muslim communities from the sub-continent. Two of the three connection points were never going to happen, and the unions were also largely hostile to immigrants perceived as willing to work for less and not joining unions.
But that’s not the whole story. Half of My own family comes from unusually poor agricultural areas in the east of the country. They voted overwhelmingly for Brexit, and are culturally concerned. That’s not because they are worried particularly about darker skinned immigrants they don’t meet, but rather a massive change in the population in their areas, almost all of whom are white Eastern Europeans. They are used to a situation where they know everyone, and all their relatives and dubious histories. They find having 40% of their local population totally alien to them distressing.
You have to remember that, unlike the US, the UK was 98% white in living memory. But that’s not the whole story. On the other side of my family, in the east end of London and south Essex, and even in the far right groups some of them associate with, there’s no real hostility towards black people, especially with the large number of mixed race people in these communities. They have lots in common, culturally, but there is massive resentment of other immigrant communities, sparked by the closure of what they regard as community hubs that have closed because the newer communities do not frequent them, though of course in some cases that’s understandable. The “white flight” is not really just about fear of the other, after all east London has been a melting pot for centuries, it’s about an influx of people who, perfectly understandably, cannot integrate into or evolve the existing culture, which makes these places economically unviable.