In reply to switch:
> My guess would be that Alun Hughes took that shot while filming Total Control, which includes the solo of T Rex by JJ.
I was going to suggest that - but then I wondered how he could have taken stills whilst also filming. My other suggestion (also already made) was going to be Paul Williams - he took the well-known shot of Jimmy Jewel soloing The Axe on Cloggy.
Jimmy Jewel's solo of T-Rex was the first time that route had been soloed, I believe.