Yes, I heard that. It's even worse than I thought: 20 storeys high required. And Nigel's scream was a smooth continuum. No articulation of sound to suggest a transition from sloping roof to freefall. I have a suspicion. He started screaming before he started falling. The only possible explanation is that he saw David starting to deliberately let go of that banner, most likely with an evil grin on his scheming face. So Nigel started to scream, first in wide-eyed terror as he saw what about to happen, and then carrying on with the scream in freefall. There is simply going to have to have been a witness to this who has yet to come forward. I was going to suggest Titcombe, but, as we know, he never speaks, and is about as real as Samantha on Sorry I Haven't A Clue. So either Freddie or Lily it will have to be...