Climbers were on Eau de Lapin or Yew Can Do at the right-hand side of Troller's Gill's main wall. As the climber was ascending or lowering off (I didn't see) there was a reasonably hefty rockfall. How big were these blocks? Hmmmm. Let me see. About as big as my cat. Big enough to kill you given that they came from a reasonable height (8m?) up the crag. The belayer remarked that he'd just been standing in the spot where they fell.