An 89-year-old renowned market researcher – described by her goddaughter as “incredibly healthy” – died after receiving treatment for back pain at a private hospital, an inquest has heard.

Jocelyn Jeffreys, of Shepherd’s Hill, Highgate, died days after she underwent a routine epidural for chronic back pain at the Wellington Hospital, in St John’s Wood, on July 1 last year.

She visited her GP after the procedure on July 4, complaining of leg pain, but the next day she became so unwell she was admitted to the Whittington Hospital in Magdala Avenue, Archway.

Tests revealed Ms Jeffreys was suffering from septicaemia, the body’s over-reaction to an infection, but a post-mortem examination could not reveal the cause of the infection.

Her consultant spinal surgeon, Mr Lester Wilson, who carried out the epidural, revealed at a Poplar Coroner’s Court inquest last Thursday that there was only a one in 10,000 chance of developing an infection from the procedure.

Ms Jeffreys’ goddaughter Sara Meyrick-Cole told the court that before her illness, the 89-year-old was “incredibly active and incredibly healthy”.

“She was 100 per cent independent, running two homes,” she said. “Jocelyn was incredibly intelligent and she knew what to look out for.”

Ms Jeffreys, who was half-Canadian, suffered from agonising back pain for five years caused by spinal stenosis, a narrowing of the spine.

She underwent several epidurals for the pain over the years but ruled out invasive spine surgery as she wanted to retain her independence.

“I felt it was pushing our luck to do something that might make her better initially but that she might never recover from,” Ms Meyrick-Cole said.

Assistant coroner William Dolman recorded an open verdict but ruled that the cause of death was septicaemia from an infection.

He said: “The unresolved question remains: where was the source of infection?”

He added: “Can I say what a doughty person she was. I am so glad she didn’t have to suffer for a prolonged time.”

Born in Croatia in 1924, Ms Jeffreys travelled all over the world as a senior market researcher.

She started her career in 1949 and has worked for some of Britain’s top firms, including drinks company Allied Domecq.

“She had such a colourful life,” Ms Meyrick-Cole said following the inquest.