Allan,
That is a good observation. Actually the rear wing was mounted to the suspension and the bodywork moved separately, especially at a corner such as the aptly named "Corkscrew" as that is almost what the car is doing as it turns left to drop away to a lower right corner to exit. This is another version of the Pete Lyons photo showing the bodywork and suspension angles.
Also here is another Pete Lyons photo from the other side of the track at the same event. Note the risks that the photographers took to get their shot.That tree would not have provided much protection !
( Ken Hyndman )