In reply to Robert Durran:
In 1980 we're doing the Blaitiere by the Spencer Couloir. We'd ditched our bags at the foot of the Couloir, and all went well to the summit.
We were decending the Ridge, which is supposed to be a scramble, but we couldn't find the route, so resorted to abseils.
I ended up at the end of the ropes in the middle of a blank vertical sheet of granite. All I could find was a thin vertical crack, so I hammered in my emergency peg, but it didn't quite go all the way. I wanted to tie it off, but the rope would be too thick, so I could only clip a krab in the eye. I clipped my harness krab to that one, and called my mate to come down.
It occurred to me then that we would have to hang the rope off the same peg for the next abseil. My mate arrived, and he hung himself off the peg too. We were both hanging off one dodgy peg in a vertical crack, nothing for our feet to purchase on, and we hung instead of standing off the rock for fear of pulling the peg out. We just about managed to thread the rope through, and I sent my mate down, screaming him to stop bouncing. The peg was in front of my eyes, and I could see it flexing and slowly levering downwards, crumbs of rock falling out from the placement. I was actually trying to hold it in by pushing it in with both my hands, even though I knew this had no effect. At last my mate got a stance, and I told him to tie the ropes off, which fortunately he did, but that didn't make my abseil any more pleasant, expecting the peg to pop at any time.