Clive,
I well remember back in the Stourpaine days at GDSF, they had what was like a big portable shed parked over a large hole in the ground, a bit disconcerting when using it, because of the delay before hearing the s**t hit the bottom :-D. H&S put paid to that sort of thing. Another classic one was many years ago at the Air Fair when it was held at Greenham Common airbase ( before the missiles were there ), the Gents was a large circular hessian screen, there was a queue to get in, once in you were confronted with a large hole in the ground and everyone standing around it, some desperate guy ran in, and had to be grabbed from falling in :shake:
Things have improved, but it is how people treat the facilities.