A couple of years ago I was at Duxford. Amongst the other visitors was a group of american ex servicemen from WW2. They had the baseball hats and some had their old jackets, with families.
There were hundreds of people dong the normal visists but you couldn't helps but notice this small band of about 40-50. A P47 was flown off and did a display for them and they were very silent. The P47 flew off and came back to the centre field with three Mustangs. As they flew over the group the P47 pulled up as the missing wingman flying into the sun. Not a dry eye in the house. Everyone stopped not just the old timers
The impact was greater as there was no warning, where the P51's came from I have no idea. After a minute they came back and the four did a display but it was moving the way everyone on the field stopped.