The husband of a woman who died from after eating a reheated Christmas dinner at a pub says the result of an inquest has finally helped him to understand what happened and “what should have been done differently”.

Giving a narrative verdict at an inquest into mother-of-one, Della Callagher, this week, senior coroner Nadia Persaud said her reaction to the toxin, which caused vomiting and diarrhoea, was so severe that hospital admittance would have been unlikely to have saved her.

Mrs Callagher, 46, of Hornchurch, died two days after eating at the Railway Hotel, Station Lane, Hornchurch, on December 25, 2012.

Speaking after the inquest her husband, John Callagher, said his wife’s death was “totally avoidable on many levels”.

“Our family and friends are devastated and disgusted by the events that led to Della’s passing away,” he said.

“Only now, three years after Della’s death are we truly understanding what really happened and what should have been done differently.”

Mr Callagher thanked the “hundreds of people” who have supported him and his family.

Mrs Callagher was taken to Queen’s Hospital, Rom Valley Way, Romford, on Boxing Day where she was examined in an ambulance and discharged.

She suffered a cardiac arrest at home later that day.

Ms Persaud explained that the “rapidity of Mrs Callagher’s collapse” from “relatively normal clinical observations” less than three hours before her cardiac arrest was largely due to the “aggressive pathogen” caused by the toxin.

Six of the seven clinicians who testified said even with earlier treatment, Mrs Callagher would have been “unlikely” to survive.

While agreeing that admittance would have been unlikely to save Mrs Callagher Ms Persaud said she should not have been assessed in the ambulance.

She said a period of observation should have taken place at A&E to give clinicians a “full set of reliable observations”.

The family’s civil claims for negligence against Mitchells & Butlers, the chain which owns the Railway Hotel, are ongoing.

A spokeswoman from Mitchells & Butlers, the chain which owns the Railway Hotel said the company will “learn the lessons” of Della Callagher’s death.

“What happened to Mrs Callagher was an absolute tragedy and the family continue to have our sincere sympathy for their tragic loss,” she said.

“We have always co-operated fully with the authorities to understand the circumstances that led to Mrs Callagher’s tragic death so we can learn any lessons to make sure nothing similar can ever happen again.”

In 2015, Mitchells & Butlers was fined £1.5 million for placing unsafe food on the market and in 2014, the Railway Hotel’s chef Mehmet Kaya and manager Ann-Marie McSweeney were jailed for perverting the course of justice.