dysgu, i am glad you posted ,
because my first thought was that adults have severe allergies as well!!
second point is that a child in that class might have a nut allergy, but the parents might want to keep it confidential.
also other children from other classes , sometimes go into the room.
siblings have nut allergies, younger siblings, so i can understand why a school would come to this kind of rule.
may be a over reaction, but sometimes it might be in place because of a individual childs risk of reaction might be higher than others. esp if other forms of health problems interfere with reaction status.
'may contain' esp in the case of chocolate is a high risk , full stop. cant judge because they have eaten it without reaction previously.
may contain , = lumps/peices of nut.
for instance , mars bars , and snickers share the same line.
common practice to clean lines between products, by using something called 're-work' chocolate. before bars are made, chocolate is pushed through the line, picking up the bits of nut/biscuit from previous bars.
Then is put back in the pot,to make the next batch of nut free choc, like for instance, diary milk bars.
when you eat a bar of chocolate , you open one end of the wrapper and then bite it. you dont look at it to check for lumps of chocolate.
so the 'may' means 'may' because some of the chocolate will not have the re-work in it, so some are free , and some are high level.
russion roulette comes to my mind, when considering chocolate bars with a may contain label.
The same system is also used for many foods, like biscuits.
i stick to the jelly sweets because of the common dairy intolerance or allergy, as well as the nut problem.
however, only use haribo from uk , rather than spain...........as they have nuts on line/site. so some have a warning.
allergies are a complicated business.