A very rare toxin, from a reheated Christmas meal caused the death of a mother of one, an inquest has found.

Della Callagher, 46, of Hornchurch, died two days after eating a Christmas dinner at the Railway Hotel, Hornchurch, where she had organised for a party of 16 to have a meal on December 25, 2012.

Giving a narrative verdict of Mrs Callagher’s death 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 had been taken to Queen’s Hospital, Rom Valley Way, Romford, by her family on Boxing Day. She was examined in the back of an ambulance and discharged.

She suffered a cardiac arrest at home later that day.

Miss 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 during the inquest argued that, even with earlier treatment, Mrs Callagher would have been “unlikely” to survive.

The causes of her death were identified as multi-organ failure, sepsis and the ingestion of clostridium perfringens – a bacteria which commonly causes food poisoning.

While agreeing that admittance would have been unlikely to save Mrs Callagher Miss Persaud made it clear that she should not have been assessed in the back of an ambulance.

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

Miss Persaud will issue a regulation 28 report, aimed at preventing future deaths, to the chief executive of Barking, Havering and Redbridge University Hospitals Trust, which runs Queen’s Hospital to recommend venous blood gas tests to be carried out on patients before being discharged.

She told Walthamstow Coroner’s Court this could “considerably improve the safety of patients and prevent them from being discharged inappropriately”.

The Railway hotel’s chef Mehmet Kaya and manager Ann-Marie McSweeney were jailed last January for perverting the course of justice. The pair had fabricated food safety records.