Imber Survivor
One of our local 'Postmasters'* in Croydon had been at Imber on the incident day. He said it was very hazy and indeed was surprised the event took place.
He first realised that something was amiss when one of the aircraft actually appeared to come directly toward the assembled observers and the wings started 'twinkling'; his words. All around him army officers started falling but he was lucky.
The aircraft was a Hurricane 11B which had 12 .303 browning guns that would have had a devastating effect on an assembly. After the Battle magazine covered the incident in great detail, and visibility, poor ground control, and lack of detailed pilot briefing were held to be responsible.
He* lived near my gliding base at Kenley, and only related the incident to me when I happened to visit his house, and realised I had an interest in flying.