Re Instructors cars:
One Sunday after a flying scrub. The famous R...k M....s was seen sitting in his car (an 1100 IIRC) static in the car park despite the fact that engine had been running for several minutes and obviously he wasn't waiting for anybody. There were a couple of other instructors as passengers who were looking decidedly sheepish.
A passing student jokingly inquired of him through the open driver's window if he was waiting for the T's and P's to come up .
"So! Wot if I am , If its absolutely correct for piston aero engines then it stands to reason it's correct for car engines."
The other car occupants manifestly looked elsewhere during this exchange.
