In reply to sutty: Iain's account was that he placed a runner at the ledge, then tested the flake, pulled up on it and as he did so it stated to topple. He fell back to the ledge, may a foot or two and the rock hit him on the side of the head, then the shoulder and arm and he then manage to push it away from him. When he looked at his arm, he knew it was broken because it was pointing in the wrong direction!
You're right, we should all test flakes, but it is easy to comprehend how on a route as well trodden as Valkyrie, after having completed the main difficulties, it's the last thing one would expect... the crazy thing is that Iain did expect it and tried to test it as best he could!
He's in surgery now, so hopefully will be able to come home tonight... I'll convey everybodies good wishes!