In reply to Rog Wilko:
I was in Wasdale yesterday and there were 3 or 4 passes of two jets over a couple of hours, heading down Wastwater. I was right at the summit of Great Gable for one of the passes, when the summit was in cloud and I couldn't see past a few metres. I thought it was going to be as noisy as the other occasions, but this was something else a whole magnitude greater - first time I've ever curled up in a ball with fingers in my ears like that at a summit! Don't know what height they were at, but it felt and sounded unbelievably close; my internal organs felt like they were vibrating weirdly, a bit like being close to an explosion and that feeling from the shock wave, except rather than one short blast this kept going for a few seconds.
Think I was still looking a bit wobbly and shell shocked a couple of minutes later when 2 guys reached the top and asked if I'd been up there for the low pass of the jet (.....there again, they might just have asked that because of the usual, er, 'windswept' hill-walking state of my hair ...)