On the contrary, non-pilots tend to describe what they saw. We pilots, I'm afraid, have a bad habit of trying to interpret what we saw and describing our interpretation of it - which can be much useful to an investigator.
If that's the case, this aeroplane approached low and fast, pulled up into a barell roll with nothing like enough height to complete, and dived into the ground near - vertically off the exit. According to a very credible non-pilot witness.
That may or may not have happened. I don't know. I wasn't there. If I had been, as an aerobatic pilot, I'm pretty sure I could positively confirm or deny that analysis. If it had spun in, I think I'd recognise that as well and be a credible witness for AAIB.
But in the past (not this accident, where the witness evidence seems remarkably consistant) eye-witness reports of accidents have all sorts of contradictory evidence - the aeroplane broke apart in the sky or it didn't, it was on fire before impact or wasn't. Often, the shock of seeing something as tragic confuses the memory. A post-flight fire becomes a pre-flight fire, it spun left, or it spun right, etc.
I have witnessed three fatal accidents, all at airshows, and in each case I was aware, long before the watching public, that the display aeroplane was doomed (it's to do with rate and angle of descent, speed, and possibility of recovery in the space available). In all 3 cases, as a pilot what happened was immediately obvious (one was a barrell roll into the ground, one was a loop into the ground, the other was a spin off a stall turn, with all the preceeding horrid loss of stability). In all instances, the evidence of non-pilot witnesses varies from pretty accurate to miles off.
Also, pilots tend to stop what they are doing and watch the entire passage of an aeroplane, so they tend to see the entire accident sequence. Non-pilot witneses tend only to look up if the sound is unusual - and might see the final few seconds and not what (vitally) lead up to the tragedy. The consistency of non-pilot evidence at Colwich might be becuase the aeroplane was said to be unusually low prior to the accident sequence, so more people looked up.
SSD