An 11-month-old girl who died in hospital was let down by “a gross failure to provide basic medical care” after she was injected with five times the required dose of an anti-seizure drug, a coroner has ruled.

Sophie Burgess was given a lethal amount of phenytoin, despite the protestations of a nurse who said it was both unnecessary and against protocol.

The baby had initially been taken to St Peter’s Hospital in Chertsey following a seizure, for which she was given phenytoin.

But the child, described by her parents as “a happy baby, always smiling”, vomited, went into cardiac arrest, and died three hours later.

The initial inquest was halted in 2017 to allow for a police investigation, but was resumed last month without criminal proceedings being brought.

Returning a narrative conclusion at Surrey Coroner’s Court on Wednesday, with a reference that neglect was a contributory factor, assistant coroner Dr Karen Henderson said: “I’m satisfied Sophie would not have died when she did if five times the amount of phenytoin had not been administered by the nurses.

“It was a serious but simple basic error that set Sophie on a path that sadly and devastatingly led to her death.

“The inexperience of the medical staff, that lay in outdated national policy that did not meet medical standards, contributed to that journey.”

She added: “Sophie was in a dependent position, there was a gross failure to provide basic medical care.”

The nurses involved could not recall who prepared the medicine, the inquest heard, nor was the dosage checked by the consultant.

The pain of her death will never leave us and we grieve for her every day

The coroner said she would write a Prevention of Future Deaths report explaining the need for medical staff to check the amount of drugs prepared before being administered, particularly when they have the ability to kill.

She also said Ashford and St Peter’s Hospitals NHS Foundation Trust had since conducted an external review and implemented all recommendations.

Sophie’s father Gareth Burgess fought back tears as he read a statement outside the inquest in which he described how his daughter’s death “destroyed the life we knew”.

He said: “When Sophie was taken to St Peter’s Hospital, we thought she would be safe and well cared for.

“Instead, we watched her die, due to their multiple failures. The pain of her death will never leave us and we grieve for her every day.”

Sophie’s mother, Emma Burgess, added: “We have always known from the outset that what happened to Sophie was preventable and we have had to fight over the last four years to make sure that the mistakes that were made on the day of her death were made known.

“We wanted to be given a truthful account of what happened on that day and now hope that those responsible will be held accountable.”

The inquest previously heard Dr Lojein Hatahet and paediatric consultant Dr Fiona MacCarthy had attempted to administer the anti-seizure drug using an automated syringe-driver.

This was not in any way a cover-up. This was the worst day of my life

It failed to work and it was decided Dr Hatahet would administer it from a handheld syringe, despite nurse Polly Leavold saying the drug was not needed and that giving it by hand was against the hospital’s protocol.

The inquest heard Dr MacCarthy had prescribed 200 milligrams of phenytoin for Sophie.

However up to 1,000 milligrams could have instead been prepared in the syringe, according to paediatric consultant Dr Mohammed Rahman, who was asked to provide his expert opinion.

In her summing up, the coroner found this to be the case.

Dr MacCarthy said she was unaware the phenytoin in the syringe was not diluted, and she trusted nurses to ensure the dosage was correct.

Dr MacCarthy also said she decided the drug was needed as she remained “very concerned” about Sophie’s condition, fearing she may suffer more seizures.

The inquest also heard that Dr MacCarthy had amended her records of the incident to show the drug was administered for an extra 10 minutes than previously recorded, but denied trying to “cover her tracks” amid concerns the dosage may have been given too quickly.

She said: “This was not in any way a cover-up. This was the worst day of my life.”

Sophie had suffered a series of seizures triggered by a reaction to infections during the last two months of her life.

She died within hours of being admitted to hospital, with Mr Burgess telling the inquest his daughter had called him “Dada” for the first time earlier that day.

Responding to the inquest conclusion, Suzanne Rankin, hospital trust chief executive, acknowledged that “catastrophic errors” led to Sophie’s tragic death.

She said: “I understand that nothing can take away the pain and grief of Sophie’s death and whilst we sadly cannot change what happened, we want Sophie’s family and other patients and carers to know that we are determined to learn when things go wrong.

“Since 2016 we have made significant improvements to the administration of phenytoin in all situations to ensure we are doing everything we can to prevent another family suffering in this way.”

Suzanne White, solicitor with Leigh Day, said: “It is unacceptable that Sophie’s parents have had to wait four years for the investigative process into their daughter’s tragic death to run its course.

“Emma and Gareth deserve answers about what has gone wrong in the police and coronial procedures for these delays to happen.”

Sophie’s was the second such phenytoin-related death at the hospital that year, following that of adult patient Caroline Pearson-Smith.