Thanks both.
Gibon I was told that the reason for no direct flight was that the runway at GVA is too short, they can't accommodate the size of aircraft you'd need to get to the Far East (although I think there's a direct Beijing flight, but perhaps that's nearer?) It may be nonsense, but it would make sense in that surely it would be a commercially viable route, so perhaps the only reason is that it's not physically possible?