Now the expo has finished, I hope my comments won't be considered as try to persuade people against flying in.
I have more than a few hours in my log books and have been to many of these (PFA rally, Aero Expo, etc) over the years but a few years ago I decided - Never Again. I steer away from other fly-ins as well.
I have seen too many near misses and too many idiots in the air. There have been incidents over the years, I remember one aircraft going down on short finals at a PFA rally just in front of me and being told to land over it (Cranfield I think).
It has already been mentioned that it is a smallish minority that fail to read the instructions. (The same ones who fly through Red Arrows displays, I suspect). However, in my opinion, it is a much larger proportion of pilots who fail to demonstrate good airmanship and cut up other aircraft, stop on the runway to read the next instruction, etc..
Then there are the difficulties of mixing aircraft of very different performance. A&C suggests it is easy as long as you all stick at 65-80 kts. In a Saratoga, you will be near to falling out of the sky at those speeds and so one minor problem that causes you to take your eye off the ASI and you will stall in. This show needs a better system for slow and fast aircraft.
Full ATC would be possible. Anyone who flew to the last fly-in at Filton had full ATC and I didn't hear any complaints. I did go to that and the aircraft were "landing after" in many cases so landing as frequently as possible. Yes, there were instances of people passing their date of birth and inside leg measurement over the RT but it still worked.
It is my firm belief that the lack of ATC is because they are simply unable to cope and have thrown their hands up to let the pilots get on with it.
It is bad enough some days just trying to join the circuit at a busy grass airfield. I have met aircraft flying the wrong way round the circuit, calling left base instead of right downwind, lining up to take off with me on finals at 100 ft, you name it. Are these the same people who load the wife, 2 kids, a huge picnic and full fuel to travel to Sywell (I saw two pilots do this on Saturday).
One day, there will be a mid-air at one of these shows. The risk is not insignificant, in my opinion, I just don't want to be part of it.