The purpose of a convenient local departure is, for me, a direct flight.
I don't want to be stopping off at EDI either enroute or on return.
I would be as well just going via LHR and getting it much cheaper.
And yes I know I would need to change aircraft doing it this way, but I still would prefer a larger aircraft once daily and direct, or of course, two smaller aircraft twice daily direct.
By738: You can still take the other flight, which operates "non-stop".
Personally I would prefer the flight via Glasgow to the trip down to heathrow and across, especially if new york was not my final destination. However it all depends on cost. If heathrow is considerably cheaper, im on the next flight