For an adult that dose would have almost certainly resulted in death

Coroner Sheriff Payne

He was immediately taken into the neonatal intensive care unit for treatment.

Within 48 hours his blood pressure plummeted and he was attached to a syringe pump which dispensed the diamorphine into his system.

The inquest at Bournemouth heard that an alarm on the machine would go off every two minutes during Harry's treatment.

The alarm could be switched off by pressing a stop button which would block further administration of the drug.

However, it could also be switched off by pressing a button that would increase the dose.

Senior staff nurse Carol Fowell, responsible for looking after Harry, said that she had received no formal training on using the machine.

Coroner Sheriff Payne said: "On 45 occasions, Carol Fowell would have had to press the button to cancel it (the alarm) and possibly, inadvertently or otherwise, her finger may have strayed from the stop button to the increase button."

But he warned the inquest jury that no-one knew for certain which nurse was ultimately responsible for pressing the wrong button.

Critical 90 minutes

It took more than 90 minutes before staff noticed the mistake by which time Harry had been given 10.1 millilitres of diamorphine per hour rather than 0.1ml per hour.

The coroner said: "The consequences were that he was given a considerable overdose.

"For an adult that dose would have almost certainly resulted in death."

It was a fair verdict and as long is it stops this happening to other people, then that is good

Sean Luff, baby's father

Harry died in the arms of his mother Zara 12 hours later.

Home Office pathologist Dr Alan Anscombe, who carried out the post-mortem, told the inquest that Harry would not have survived even without the massive drug overdose because he had brain damage.

Mr Payne added that although the drugs had been a contributory factor they should not be considered the primary cause of death.

"What we have here is a seriously ill baby in the neonatal intensive care unit and the evidence shows that he was under total care in the course of his life but an accident happened - for which the person responsible has been deeply regretful - which could be as a result of a lack of training or a mistake."

The jury of four women and seven men took 90 minutes to reach an open verdict.

After the hearing, Harry's father Sean Luff said: "It was a fair verdict and as long is it stops this happening to other people, then that is good.

"It was a tragic accident I think but I certainly feel that hospital staff need more training."