Earlier this month, an inquest concluded Hannah died after a “failure to follow the processes in place to discuss allergies” and a “failure of communication” between the coffee shop staff and Hannah’s mother.

Hannah and her mother had bought a hot chocolate from a Costa Coffee branch in Barking, east London.

Her mother said she ordered two soya hot chocolates – which was disputed by the coffee shop worker who made the drink during the inquest – and had asked staff to clean the equipment they were using.

The inquest heard the hot chocolate may have been made with cows’ milk and Ms Duyile was not shown a book, which included ingredients of how the drink was made.

The teenager later became unwell in a dentist surgery after taking one sip of the drink, and shouted: “That was not soya milk.”

Ms Duyile then rushed Hannah to a pharmacy, where she passed out.

A post-mortem examination found Hannah died after suffering a hypersensitive anaphylactic reaction triggered by an ingredient in her hot chocolate causing an allergic response.

The inquest also heard evidence from Costa employees about their online training on allergens, including from one who said they failed the quiz 20 times before passing.

“Everybody needs to change their ways,” her mother told the BBC. “If you’re training somebody, they can’t understand the allergen on the company website and it’s taken them 20 times to do it over again, you need to ask yourself , ‘[is] something off here?’

“Your staff should know what goes in everything.

“This should be a common basic thing. Every single person [in] restaurants, coffee shops need to know.”