Sadly a similar event of falling masonry happened just up the road from me a couple of years back at a restaurant. I seem to recall visiting a west end theatre at some point (prob 4-7 years ago) with a 5m by 5m section of truss with netting taut under the dome - I can't remember which theatre it was but it would be a real shame if this was implemented across many theatres although the discussion about control measures for mitigating this type of risk will certainly be quite interesting - particularly as the ceiling cert was only 3 months old.
