There is more support/allegiance for Blues within the City of Birmingham than there is for Villa.
A lot of Villa's support is from outside Birmingham.
That is not correct. Birmingham is more or less split, north & south. South Birmingham being Blues, north Birmingham being Villa. With all their years in the wilderness, more and more Villa have cropped up in south Birmingham over the past 25 years. It is very rare to see Blue colours in north Birmingham though. There are undoubtedly more Villa in Birmingham than Blues although, like everywhere else, a large portion of the support (for both teams) comes from outside the city.
Times have changed-People are moving further away for a variety of reasons. Birmingham is completely overrun with foreign immigrants, many od whom have no real desire to integrate. The schools are poor and the traffic is horrendous. I moved out in 2007 and have never looked back-Absolutely hate going there now