I think that this accident may be the beginnings of a change seen after the 1952 Farnborough accident with John Derry and Anthony Richards flying a DH110. That was the last major 3rd party loss of life at a UK airshow (4 times today's fatilities). Pretty much all of today's rules and regs in CAP403 come from Duncan Sandy's inquiry into the 1952 crash.
I must admit, as a Display Director, some display venues have made me feel distinctly uneasy of late when considering the local area at certain venues. Indeed I have displayed at Shoreham about 10 years ago and remember seeing Lancing College close by (the big imposing structure in most of today's tragic pictures) and thinking what would happen if I crashed into that! More recently, some of the camp sites and unofficial spotters enclosures that have sprung up around RIAT have also made me raise an eyebrow - they kind of make a mockery out of the 'crowd line'!
Accidents like the ones we have seen today and with the recent Gnat fatality show that the display venue either needs to have a more sterile display area (ie. not over the venue entrance and a major road) or at least to a higher height above the ground to give the pilot more options should there be an issue.
Very sad to see and such a tragic and needless loss of life, in my humble opinion. My condolences to all involved.
LJ