Leon has called for an industry-wide standard for allergen information, after an inquest into the death of a girl from an allergic reaction found Pret a Manger’s labelling was “inadequate”.

Natasha Ednan-Laperouse, 15, went into cardiac arrest on a flight after eating a Pret sandwich at Heathrow Airport which contained sesame seeds.

Coroner Dr Sean Cummings said he would be asking the government whether large businesses should be able show reduce food labelling for products made in shops.

Pret chief executive Clive Schlee said the company was “deeply sorry” for Natasha’s death, and vowed to learn and seek “meaningful change” from the tragedy.

In response to the conclusion of the inquest, which criticised Pret for its allergen information labelling, Leon proposed sandwich shops, restaurants and fast food brands develop an alert system to notify everyone of any accidents or issues immediately so that lessons can be learnt straight away.

A Leon spokesperson said: “It’s all of our responsibilities within the foodservice industry to keep everyone safe. We believe the best way to do that would be an industry-wide standard for allergen information. This needs to be simple and easy to understand. For example today a sandwich shop that makes its sandwiches in the shop does not have to provide allergy information on the packaging. But a sandwich shop that makes its sandwiches in a central ‘factory’ does have to do so. This is confusing for you, the guest.

“We are also proposing to our industry colleagues that all sandwich shops, restaurants and fast food brands develop an alert system to notify everyone of any accidents or issues immediately so that lessons can be learnt straight away.”

Leon qualified its statement by adding that all its kitchens use ingredients that contain nuts, peanuts and sesame, which while segregated, could never be 100% safe for those with a serious allergy.

Clive Schlee, Pret chief executive, said: “We are deeply sorry for Natasha’s death. We cannot begin to comprehend the pain her family have gone through and the grief they continue to feel.

“We have heard everything the coroner and Natasha’s family have said and we will learn from this.

“All of us at Pret want to see meaningful change come from this tragedy. We will make sure it does.”