Whilst this is a tragic accident, I have no doubt the AAIB will do as thorough a job as they always do, though I would not envy the team the unpleasant circumstances they're likely to be encountering at the moment. There's not a lot of point repeating others valid comments, although there may be a few questions that don't seem to have aroused much query.
1. Any significant airshow attracts a large number of people around the wider perimeter/area, either trying to get a better vantage point for their filming, or to avoid the ticket price. They often position themselves deliberately under, or beyond, the display line to maximise the thrill; experience; photo location etc. . . and RISK!
2. I believe all airshow Directors in the UK are obliged to issue a display authorisation to each pilot/team, although I also understand that one Director may be able to pass on such authorisation for other airshows once practiced & performed (happy to be corrected on this). I would expect this display will have been scripted so that both pilot & commentator would know the order and type of manoeuvre being performed?
3. From my aerobatics many years ago, a loop was always a continuation of the entering direction of travel - I do believe this pilot pulled up heading approx 200 deg but impacted heading approx 020deg, all parallel with the 02 runway as per the display line. NOT a "loop the loop" by any description, though I'm no longer familiar with the correct term. If I've completely mis-interpreted the camera angle, I stand to be corrected.
4. I would also wonder what height/speed one might expect to enter such a manoeuvre, as it will have required a certain vertical requirement, in the conditions of the day, the margin of which could be as little as 20 ft between spectacular & disaster?
I've personally witnessed two aircraft spear-in at airshows, and knew they didn't stand a chance when my stomach contracted a number of seconds before they impacted. Both were fixed wing and trying to pull tighter having effectively mis-judged their line/wind/height/performance. It's sadly quite obvious to many aviators, and horribly unsettling on every occasion, particularly if one is due to fly shortly afterwards. It's also very sobering and reminds us that we hold a huge responsibility to operate as professionally as we can every single time we get airborne. I've viewed footage of many others, often in tandem with reading the meticulous reports generated by AAIB and other nation equivalents in order to learn the lessons from the misfortunes of others. Vary sadly, in due course, we're going to have to learn some more lessons from this one.