After severe reaction and ambulance to A&E just before Xmas, I finally had the appt at clinic today. Scratch tests etc duly done and nada in the way of reactions. Not even to pollen, despite being a hay fever sufferer. I've suspected peanuts for a few years but no reaction there either. Consultant thinks it is most likely to have been an auto immune response rather than an allergic one, though advises continued caution with possible trigger foods (peanuts, honey, goats cheese).
But what he did say which was both interesting and worrying, was this. Epipens were developed for use in cases of exposure to nerve gas during the first Gulf War, so were intended for young, fit, mostly male soldiers. Even v slim women naturally have too much fat on their thighs for the needle to penetrate the muscle and deliver the adrenaline to where it needs to go to halt the reaction.