bruffin you made an assumption that the child who had nuts thrown at them was in a school with a nut ban - I don't know for sure but probably not. I do know that it has a nut ban now. Nut allergic children don't get nuts thrown at them now because the children know what would happen if they were caught with a banned food.
It is NOT nut bans that feed complacency. Adrenaline does not always reverse a reaction - something the parents of allergic children prefer not to think about. Therefore the only safe strategy is avoidance. If you have a nut ban there is less nut protein to avoid. You are fostering complacency by suggesting that it is possible to "manage" an allergy without avoidance.
As for the Anaphylaxis Campaign not being aware of those allergic to very small amounts or to smell - they are closing their ears to it. I know that because I have e-mailed them about such people (I've met/ corresponded with some). I'm not a member of the Campaign, they represent only a small proportion of the anaphylactic.
The Cambridge nut allergy study is great but involves very small numbers of children who are able to travel to Cambridge frequently over a 6 month period and less often afterwards. It is hopefully being extended and may cover adults. It isn't available in the rest of the country. One adult died in this country when a stupid alternative practitioner tried the same route without understanding the risks.
As for American peanut bans - there is a sunflower spread alternative to peanut butter. Cheap, nutritious and probably developed for the American market.
School trips are definitely a problem. Despite ensuring the organisers were well aware of the problem my child was given food containing nuts on a school trip. They are well trained, the nuts were obvious and they didn't eat it but they would have gone hungry if I had not sent emergency food supplies. Medication should always be on the child once they are old enough for school trips, although a back up with a staff member is good.