G. whilst I agree safety at airshows needs updating and a more through check and risk assessments undertaken. I disagree that the cause is the least important part of the AAIB investigation.
The AAIB role is to establish the fault and make recommendations to reduce the risk of future accidents, whether they are participating at airshows, practicing, training or just flying from A2B . They look at the whole picture and see if there is something that could be changed/tweeked that would reduce the risk regardless of were the aircraft is.
If the fault is down to poor maintenance of an aircraft then just reviewing airshows will not stop future accidents. Unless the airshow organisations undertake an inspection and review of each single aircraft to ensure they are fit to fly. Which they won't/can't so rely upon, like the CAA, for the maintenance organisations to follow manufacturers recommendations/guidelines and the relevant licence agreements.
It is unfortunate that this accident happened at an airshow but the airshow wasn't necessary the reason for the crash, the airshow organisers had covered the safety of those paying as they are required to do so and so had the pilot by maintaining the crowdline, it is with hindsight which is a wonderful thing that maybe the area near/over the A27 was not deemed as high risk like the college.