FL - appreciate your well posed responses.
Simplistically, is it not the case that the regulator and governing body (CAA) failed to react to the changing nature of air displays in the UK?
I'm not a pilot, but I have attended many displays across the globe over the last 35yrs, and this kind of occurence was more a matter of when not if.
For example, as recently as the Gnat accident at Oulton Park (which I witnessed), there was opportunity to "call time" on the lax regulations that governed displays by privately owned vintage high performance jets at UK displays.
Honestly, who here could ever be comfortable with high performance, swept wing, ex-mil jets being flown at public displays in high energy manoeuvres, by part-time FJ pilots with low type experience, low currency, sometimes in formations, flying un-briefed routines in sometimes marginal weather at unsuitable venues?