Your point was perfectly valid. The cities, almost universally, voted Dem. And they are the areas with the most diverse voters.
So the people afraid of diversity are actually those with no experience of it.
And I agree with you here as well - I will add that a lack of education and financial disparity are the underlying cause for the racist decisions made both on this and that side of the pond. And I will indeed call Brexit and Trump decisions what they are - fueled by racism, scapegoating problems on an invisible issue. It needs to be called out, even in an era where doing so makes you a minority voice.
The UK probably does differ to the US in this instance.
i.e. 'middle England' - the towns and cities that aren't major university hubs for example - are the areas that swayed Brexit. I know, i'm from one of them, and almost universally the vote was out. But, the difference between the UK and US in this case is that in the UK, due to size more than anything else, I think most areas can claim to be 'affected' (both positively and negatively, btw) by immigration.
I'm from Wakefield. Much of the local population is made up by ethnic minorities or immigrants. I don't think there's anything wrong with it.
However, I also accept and acknowledge the fact that in the areas that have the most immigrants in (there are several areas that are 'exclusively' segregated - but such is life), there's more crime, there's a higher poverty rate (due to large-scale organisations exploiting lower wages etc), lower life-expectancy... I could go on.
Now, that's not to say that all of the criminals in my area are immigrants or from ethinic minorities. I'm sure a large number are local divvies and scroates who shouldn't be allowed to breathe, but there are definitely issues.
Rotherham is another example. The politcal correctness of an inept police force unwilling to do what needed to be done, and much of that was due to race.
So, my original point was that, in the UK, the 'backwater' towns and cities have an experience of immigration. To say that these places don't is a bit insulting, and it's a point that I have had many arguments about with people who live/work in the major cities.
In the US, I think it's clear that 'middle America' genuinely means just that. Low numbers of immigrants, real 'backwater' towns and cities out in the sticks. Their exposure to immigration likely is very limited - and Trump knew that, acknowledged it, and made sure he hammered home the point.
That won him the election.