The dental nurse – who “religiously avoided” dairy after a prior near-fatal experience – suffered an anaphylactic reaction and died.
Avon Coroner’s Court, in Bristol, heard the coconut yoghurt dressing, supplied by Planet Coconut, had been cross-contaminated with milk protein.
Yesterday senior coroner Maria Voisin said: “Celia Marsh was not aware the wrap contained milk protein.
“The contamination arose during manufacture. The manufacturer of the dairy-free yoghurt had in its possession documents which flagged this risk, but this risk was not passed on to its customers.”
Mrs Marsh’s widower Andy of Melksham, Wiltshire called for tighter UK testing of food for allergy sufferers.
Mr Marsh, 51, said: “Any manufacturer who makes something labelled “free from” has to take the responsibility for the testing to make sure it is exactly that. I want testing at every stage to make sure nothing gets through.”
Pano Christou, CEO of Pret A Manger, said: “Planet Coconut had information which should have alerted them that their yoghurt may have contained milk. If Pret had known, we would have never used the ingredient.”