We shouldn't allow this to turn into an East-West slagging match.
However, having worked at both GLA & EDI in my time, I think that we should remember that GLA has been the only airport in Scotland to offer year round transatlantic flights for quite a few years now.
Why? - Could it possibly be better facilities, greater transport links to West/Central Scotland, larger poulation (bigger potential market, etc)& Industry.
Things have quite obviously changed over on the East Coast - A new terminal (dominated by BA!), more importantly the Scottish Executive is now based there, and the attitudes have become that they think that there should be greater links to the outside world, further than BRU/DUB/FRA, etc.
When AC/AA/CO, etc, decided to operate from GLA they obviously did their homework and found that this was where the greatest potential market is, and not EDI.
Joe - I have to agree with you - most of the flights operating from EDI are busier than some of those operating from GLA. easyJet & GO are really doing quite well. The old saying 'Short Arms, Deep Pockets', does seem quite appropriate doesn't it?