It's absurd. I think I read a couple of months back that Virgin had changed some of their holiday flights from Florida to the Carribean, simply on UK tax reasons! It's also cheaper tax-wise to fly via most european countries over the atlantic, even though twice as many flights are involved.
I was at a talk with Willie Walsh a few weeks back (where he was very open about the unannounced BMI bid!) and he made it very clear he did not think the Government fully understood the effects of taxing aviation.
Hopefully Mr Cameron will wake up and do something about it, though somehow I doubt it!