Does seem too simple - and is clearly wrong

Even looking at the last few examples in this post:-
Duncairn Avenue - Urban 3 - postcode BT14
Seaforde St - Urban 11/16 - postcode BT5
Belfast Urban 7 (according to the notice on the wall at the General Registrar's Office) is the Greencastle/Whitewell area (postcode BT36) - BT7 is the University area (Belfast Urban 6).
