So much could be said in sadness, but I'll restrict myself to this: I did a bit of an interenet search and ended up at Wikipedia (FWIW*). I could find very few casualties recorded amongst non-participants (by which I include spectators, whether official or unofficial), and none in the UK.
Is it really correct that this is the first time ever in the UK that passers-by, unconnected with the display, have been killed or seriously injured by a display accident?
MB
*
https://en.wikipedia.org/wiki/List_o..._and_incidents