Ever since the first private jet collided with the accountants and the auditors, we have been hearing about how these aircraft are really, really, a productivity tool, certainly not a luxury good.

No indeed. Never mind the place of private jets in luxury market surveys, and their over-representation at the Aspen and Palm Beach County airports. To make the point, server farms full of pro formas and comparative cost what-ifs are running 24 hours a day around the world, just to be ready for any tax man’s surprise visit.