We were absorbed in a balletic reconstruction of how Italy had invented steam power and the telegraph. On stage, 30 athletic young women were dressed as bellboys, their bright red tops, red and black caps with pompoms and blue knee-length shorts, creating all the disturbance most of us needed. However, unknown to us, engineers were looking worriedly at one of the 441lbs, 12ft by 6ft glass panels, and at those sitting under it.