Filming was done over four near-sleepless days in a Paris studio, after one month of script approval, two months of concept drawings and a further four months of development and testing. One of the more surprising things about the ad is that it was not a cheat. Although it would have been much easier to fiddle the chain of events by using computer graphics, the seesaw and shunt of events really did happen, and in one, clean take.

At one point three tyres, amazingly, roll uphill. They do so because inside they have been weighted with bolts and screws which have been positioned with fingertip care so that the slightest kiss of kinetic energy pushes them over, onward and, yes, upward. During the pre-shoot set-ups, film assistants had to tiptoe round the set so as not to disturb the feather-sensitive superstructure of the arranged metalwork. The slightest tremor of an ill-judged hand could have undone hours of work.