I was climbing the HS 'Honister Wall' on 11/07/2020 at Buckstone How and had a very narrow escape when I lent back on a cluster of blocks/flakes at the end of the overhang on pitch 2, just as I was starting up the arete next to/below it, and they completely gave way. I had just climbed underneath this cluster and luckily didn't test and of the holds above me or try to place gear there. The largest flake, which was bigger than me, fell over my shoulder, snagged one of my ropes and severed it halfway through the core. My belayer and I felt the rock come tight, braced, and luckily the rock continued downwards without pulling us off the climb. The rocks landed at the belay at the start of the climb, gouged out a large patch of turf and continued off down the hill. Luckily I didn't run pitches 1&2 together so my belayer was no longer standing there. We promptly bailed from the next tree, trying not to touch any more rocks on the way! I checked my guidebook again afterwards and it describes the rock as something like 'comfortably solid despite its reputation'... I was ready for some loose holds and found plenty, but unstable rock to this degree came as a bit of a surprise. We cancelled our trad plans the next day and went bouldering instead.