> General rule seems to be that places with lots of university students or large businesses tended to vote remain and those with either deeply conservative populations or a lot of immigration tended to vote leave

Doesn't think that is true. Lewisham, Lambeth and Tower Hamlets are some of the places with the most immigrants and remain won in all of these places by obscenely large margins.

Maybe votes were more along racial lines - White English (especially the older ones) voting to leave, but people with a more colourful Asian/Caribbean heritage voting to remain?