The boss of Pret A Manger has told ITV News he endured the "worst period of his life" listening to testimony detailing the final moments of the teenage girl who died after eating at the high street food chain.
In his first interview since the allergen crisis, Clive Schlee said the shock of Natasha Ednan-Laperouse's death had generated the biggest change in company policy in Pret's 30-year history.
In response to the tragedy and subsequent criticism, Mr Schlee said Pret was now commencing a nationwide roll-out of full ingredient labels on all products.
Emily Morgan's exclusive report reveals the extensive campaign undertaken by Natasha's parents to push for labelling change
The decision by Pret could force other high street food outlets to follow suit
Bakery chain Greggs has backed full labelling of products but said any change would not be overnight
"The last six months have been an intense period of change and they have been tough but I am pleased we are making those changes and changing the system is very important to Pret," Mr Schlee told ITV News Health Correspondent Emily Morgan.
He added: "Everyone in Pret has felt that burden. Pret is a very real company with very real people and we were shocked."
Natasha's parents welcomed the move, in what is a significant victory for the campaign they launched in their daughter's memory. They have now urged other major food retailers to follow suit and for the government to enshrine the policy in law.
"We hope the entire industry steps up to the mark," Nadim and Tanya Ednan-Laperouse said in a statement to ITV News.
Pret has come under fire for failing to deal with previous complaints regarding allergens in Pret products.
Mr Schlee said the system had now changed and that "we all know about it" if complaints are logged at Pret.
Under the current regulations for items made in-store, general allergen warnings can be posted around the shop, rather than on packaging, and for specific advice to be given orally by staff.
Pret has now gone further than the existing regulations by listing full ingredients on its products, including allergens, which will be rolled out across all stores by the end of the year.
Despite the changes, Mr Schlee said "there can be no guarantees" may suffer an allergic reaction after eating at Pret, but promised the chain would always provide the correct information to customers.
"Everyone understands that allergies are an area in public health that people don't know a great deal about, it's still a very emerging area so there can be no guarantees where allergies are concerned but what we can guarantee is you'll get the right information," Mr Schlee said.
"Our responsibility is to make sure you have the accurate and right information and we take that very seriously indeed."
He also called on other companies to follow suit and ensure as much information is given to customers so they can make informed choices about their food.
"I would encourage them to do that yes...I think you need to know what you are putting into your sandwiches and if you know what you are putting into your sandwiches you can give information about them. That is Pret's position."
Following Mr Schlee's comments, Natasha's parents said: "We believe the time has come for full information and transparency about what is in our food as proposed by the Environment Secretary, Michael Gove, during the current consultation on Natasha's Law.
"We hope the entire industry steps up to the mark and supports our call for full ingredient and allergen labelling in pre-packaged food because no family should ever have to suffer the pain, anguish and dreadful death of a child as we did.’’
Last year, they met with Gove to discuss changes in the law to ensure all pre-packaged food clearly labels allergens on its ingredients.
Her father Nadim Ednan-Laperouse told ITV News at the time that he was “really surprised at just how welcoming he (Michael Gove) was to listen to our concerns.”
“The good news is that he was really on board with everything we were saying and wants to see positive change himself as soon as possible."
He added: “We are calling for Natasha’s Law – it is symbolic to honour her and her death and also a rallying call for everyone who has allergies in this country.
“The law as it stands today and has stood for a number of years has been very, very weak and it’s allowed some companies like Pret and indeed others to follow that weak law and grow their business to a substantial size – at the same time – holding the public at great risk of harm and that loophole or ability to hide behind that weak law is about to change.”