Thanks. My girlfriend is a doctor and sorted me out when I had the severe reaction, so I have a reasonable knowledge of the area, although the CAA may differ! I should probably add that I didn't have a full anaphylactic reaction, just felt pretty crook and did walk myself into and of course out of the clinic when I had the reaction. Hydro-cortisone and O2 had me sorted in a few minutes and I was in and out in under an hour.
My logic (perhaps biased) is that I am tested and know what to avoid and carry the right equipment should I be inadvertently exposed and subsequently suffer a reaction (which is of course not a given anyway). The day before even and for years before that I had been eating pretty much anything I liked without any problem, could mean that anyone might have the same problem in-flight unless they have been pre-tested as being 'zero' to everything...
Seeing an AME tomorrow with all of my immunologist reports, so hopefully that will be the start of getting this cleared up, but I'll keep updating this thread as similar questions seem to have appeared over a number of years, but without a final outcome being posted (I used the search function before posting :-) )