Thanks for all the comments - I'm a bit behind in replying to them all

Any feedback is welcome; as Rob said you don't really improve without it, and I appreciate the time people take to write it. I happen to also think the Peak Cavern shot looks a bit odd...
mrodoc - Nice photos. I think the P40 is actually the highest Dent de Crolles entrance, although not by much (the Therese is maybe 10 metres lower?), but I may be wrong.
spikey - The Bournillon picture lit by carbide is lovely. I think carbide as a lighting source for photography can be very effective. Some of the Salamandre photos I posted (actually the first underground pictures I took on digital) were partially lit by carbide as well.
christine - The Neuf Gorges does indeed sound like the one you refer to; it is in the Ardeche well into a forestry plantation, and not at all easy to find if you don't know where it is! It took us basically a whole day to find the cave on the first visit. There are ways of getting pretty close to the hole in an average car, although some care is required - drop me a mail if you want more details (mark@three-tuns.net)
I've uploaded a few snaps of Ogof Draenen this evening. More to come ...