Each year, about ten people in Britain die from allergic reactions to food. The case of Natasha Ednan-Laperouse, who died after eating a sandwich from Pret a Manger, was a nasty reminder of how allergies can claim young lives at any moment. But it also raises a difficult question: to what extent are businesses that serve food culpable? Why do so many people, after this case, want to blame Pret and only Pret? It’s territory with which I am familiar, as a mother of two children with severe allergies. When Alastair, my son, was eight years old we attended one of the first allergy clinics at Addenbrooke’s Hospital in Cambridge. They inserted small slivers of chicken, turkey and pheasant into cuts in his arms and measured the allergic reaction.