Well, to start with I can say it's the single best musical event I've had the utter joy to be involved with in my life, bar none. I did have a blast in every sense of the word.
Our group gathered at Aldgate from about 11, those of us who hadn't registered did so, and we got down to the serious business of chatting to fellow players, checking out horns etc. All kinds of people were there, a lot of older people like me (and beyond!) but plenty of younger studenty types and some pretty young kids too, a very good mix really.
For ease of transportation I took along my curved soprano in a bit of bubblewrap in my laptop bag complete with shoulder strap, mainly to avoid the hassle of finding my case among hundreds in the vans at the other end. Many others had arrived with horns of different sizes (including a few baris) with back-pack cases.
There followed a bit of informal 'practising' i.e. playing the main phrase to your own 'internal time' in smallish groups, or generally tuning up/mucking about etc., during which time I found I had been 'cornered' by a film crew of some sort who had focussed quite tightly on the bell of my little curly sop, and was asked a couple of questions about it to camera to my surprise. I think, although there were several soprano players in the group, mine was the only curved one and seemed to be drawing attention from some quarters.
Next up, we had a slightly more formal 'rehearsal' to get an idea how the 'phrase/improv around the scale then repeat' part might sound, plus a run through of the more structured part of the piece. More than a bit messy, but I think the conductor/instructor liked it like that.
Following that, we moved off down the route, playing the piece to our own internal time and crikey what a glorious, joyful, chaotic racket it was! We were close enough together to hear each other, sort of, so some ideas and improvs were clearly being tossed around from one to another, but the overall impression, especially to the bemused-looking onlookers must have been one of an unholy din, which of course was what it was supposed to be.
Every once in a while we'd stop processing (but not playing) presumably to regroup until we found one time we had stopped at the coming together of all four groups, at whoch point the noise definitely increased and became even more chaotic, as we were playing in four different keys, nominally; it may as well have been a hundred and four. Up til this point there had been something utterly hypnotic about making such a joyful racket among so many other people - occasionally stopping playing just to listen for a while before diving back in - which increased as all the groups moved towards Marker 1 at the north side of the bridge.
As we passed the Marker, all improvisation stopped, and the relatively simple phrase was taken up by everyone, again in their own time/tempo. So, no decrease in volume but a somewhat less disorganised sound as everyone by that time was at least in the same key.
We then came to a halt, still playing the phrase, in front of the conductor's podium, where he attempted to conduct the written part of the piece. Due to the fact the column of players was stretched a way back from the podium and sighting John Harle may have been a bit difficult for some, this part of the piece was quite messy (but in a really good way) but at least harmonically accessible (in theory anyway). After blasting out the final few conducted chords, we processed off the bridge to the South, all playing a low concert C in unison with a gradual decrescendo as we left the bridge. This part, after the chaos and raggedness of the past half-hour or so was unbelievably haunting and moving, and I left the bridge feeling totally blissed out and strangely calm.
All in all, a life-affirming, life-enhancing, and maybe even life-changing experience which I'd love to do again if the opportunity arose, and I met some damn fine people along the way.