[FlorayG]

I recently flew with Aer LIngus and they announced that as there was a nut allergic person on board they would not be serving any and would people please not open any packets of nuts.
However I do think most people don't realise how severe these allergies can be. They might ask the person right next to them "Is it you?" and if the answer is "no" they would think it's OK to eat nuts then because they're not near the allergic person. After all, most allergies are only triggered when you actually eat the offending allergen so that's what people think.