I think you'll find the Duty Free adverts are temporary - the real deal has only recently been concluded and the copy wasn't ready for last night.
So, it's actually a commercially funded project that has no impact on airport charges.
thegoaf - my experience is that the horrendous queues at Gatwick are usually for Check In, especially MYT and TCK, although I did queue for 40 minutes for BA in North Terminal this summer, and then breezed through security.