It's already been said but the APD will mean people won't fly long haul from UK.
Already know 2 cases personally of people flying to Amsterdam and then going long haul from there, thereby saving at least £150 on the total fare, not to mention the drive to LHR since they flew from their local regional airport.
Ironically in one case the a/c from Amsterdam to Barbados landed at Gatwick on the way - so much for "green" taxes.