This is a two pitch route, if you haven't done it, get on it, it is one of the best routes in the country; I almost fell off laughing). The mid height belay is formed by a constricted stance (when you have 3 people) on top of a chock stone at the front of a cave. I led the first pitch and being out of slings built the 3-point anchor with the ropes. In order to make the stance more readable (which given what happen is somewhat comic) and easier, when the second (Pete) arrived I rebuilt the belay using slings he had cleaned to facilitate tying 3 climbers into a powerpoint and swapping ends of the rope so Pete could lead the final pitch. The third arrived and clipped into the powerpoint. The stance is constricted, the cave and powerpoint dark, the light from month of the cave bright. Pete is tied in with a rope, I'm tied in with both ropes, the third is tied in with one rope. Pete went to clip directly into the powerpoint with a daisy (PAS-style). This was difficult for him as the powerpoint was below him and out of sight, it was also under a mess of other ropes tying us in, or going from me to the anchor pieces. Given this difficultly I grabbed the PAS and clipped Pete into the powerpoint. A while later Pete found his PAS was not clipped to the power point, yet its twist lock carabiner was. And hence he was probably not tied to the cliff (assuming at this point he had untied his first attachment point, I can't remember). Falling off the chockstone would be fatal.
On a sunny bank holiday I was photographing my friend climbing at Mother Carey’s from an abseil rope. The tide was coming in rapidly and quite a few groups were on the face finishing their routes. A climber in the cave which is an optional belay on one of the routes shouted to me asking if, from my vantage point, I could communicate with his second- a combination of the sound of the sea and the angle of the rock meant that he was unable to let her know that he’d reached the cave and was going to belay from it. Matters were complicated by rope drag which meant that he could not tell how much rope he had pulled in. At first I could only see the ropes leading down and out of view but soon I was able to let him know that his partner was climbing the pitch and was actually not too far from reaching his stance. He did not receive this news as cheerfully as I expected and the reason became clear as I saw him hurriedly attach his belay device to the rope- he had not anticipated that his second would have started climbing and, unbeknown to her, she had effectively soloed the pitch!