That "wee jolly" to London can cost 162 pounds one way (just to see it cancelled) for important business - plus it could be to connect to that "jolly" flight to Sydney or wherever.
European services by BA have a trend to be operated over and above domestic in terms of weather issues or bottle necks at LHR. I do not believe for one moment (and I have experienced it) that AMS,CDG,DUS,FRA,BRU etc get cancelled before or at similar times as GLA and EDI.
Nivsy