A-H,
I think you are stretching the imagination a bit with a New York scheduled flag carrier, as much as it would be nice for the east coast it would be highly unlikely (viz LGW against LHR), however agree with the other route sentiments.
As to the North/South thing it is an interesting thought, where does 'THE NORTH' begin. Some say it is as soon as the accent changes, so to Southerner's in Sussex, Bedford is OOP NOR'.
Methinks, where does the 'Brummie' accent die and the 'Ayuplike' begin, maybe anything north of the A50 is a possible demarcation line. No doubt it all goes back to Henry and Richard!