I’d say that the cultural mix of the cities, as @villa4europe alluded to, also plays a big part here these days. Birmingham is a very multicultural city, and quite a portion of the asian population, from my experience, supports the likes of Man Utd and Liverpool in particular. I’m not wishing to generalise here, I have a number of Asian work colleagues who are Villa fans too, but one of the reasons I hate losing to Man Utd or Liverpool is having to face their ‘fans’ at work on Monday morning. And I work in Birmingham city centre.
Certainly, that’s the way I see things in terms of my own work colleagues and neighbours. When I look back to my childhood in the 1970s and early 80s, that wasn’t the case; the majority of people in this city supported Villa, Birmingham, or to a lesser extent West Brom, dependent on where in the city they were located.
My wife is a Geordie and I spend a lot of time in the North East. Whilst things have changed a little, there isn’t the same cultural mix in Newcastle and the people there, and in the surrounding areas, are overwhelmingly Newcastle fans. Walk around the Metrocentre in Gateshead and it’s a shock to see a kid in a Man U or Liverpool top. Walk around Merry Hill centre and you’ll see kids in Wolves, West Brom and Villa tops, but just as likely Man U, Liverpool, and tragically now even Man City tops.
So, in my opinion, that’s what makes someone from Birmingham more likely to support Man Utd than someone from Newcastle is.
I hope that doesn’t come across as controversial or contentious, that was absolutely not my intention, but I do think it’s part of the reason as to why Newcastle, combined with its remote geographical location, has a loyal and partisan following within its potential catchment area.