Was detached on a course to a first class training establishment not far from Weston Super Mud in the late 80's, when the hooter went off at 04 Chr!st sake. Our entire class (all techies from a number of stations) rolled over and went back to sleep, then wandered off for breakfast at the usual 07:00. A high ranking station SNCO dressed in well pressed camo gear had a bit of a sense of humour failure when he saw us, until we pointed out that in the event of the real thing we would all be three hours up the road to our home bases (We had been primed by our instructors the day before that we were just to ignore all the noise)
For some reason the exercise finished at 07:30 precisely, the trainees then went off to class for the day, and it all resumed again at 18:00 for another three hours....
I was a trainee at this establishment when another of these regular pointless exercises was planned. Unfortunately for the DS, we got wind of it and when the hooter went off at 0400, aprroximately 2/3 of the 600 trainees were still out in Weston. FS Regt went scripto when people started arriving back on Stn for breakfast. He managed to get the exercise rescheduled for the following week and we were all given an order not to leave camp.
Bear