I read the notes on Popham's website and set off. As far as 'instructions' go they're pretty simple, certainly nothing like the multi-page AICs that you used to get for the PFA/LAA Rally. I've copied one of the key paragraphs here.
When you call up all we want hear is Call-sign, Aircraft type, and where you are, e.g. “G-CCYR, is a C42 microlight, 4 miles north for joining instructions”. Do NOT use “understand we are using blah, blah, blah, QFE blah, blah” because a) you might NOT have understood, or b) the information might have changed. If you have the numbers then don’t ask for further joining instructions! By all means call “G-YR downwind” but do not call “number three”, downwind”, as you might not be able to see everyone in front of you! If you are baulked then go-around and do not argue on the radio – we all make mistakes!
Like the paragraph says, we all make mistakes, and I'm not a fan of criticising other pilots, but I was surprised by how many people flying in hadn't read the above. I reckon only about 10% of the traffic came close to meeting Popham's request. The poor guy on the radio (who I thought was doing an excellent job) was spending a lot of time asking supplementary questions - "what type, where are you, registration etc."
The departure experience was similar with a lot of stuff being repeated several times.
It all worked out in the end. The experience was a good one, the organisation efficient and the show worth visiting, at least for a few hours but I'm still left wondering why a lot of people just don't bother to brief themselves before flying in somewhere like this.