His mistake as a junior came a few millimetres from killing a patient.

Dr Hammond was in his final year as a junior doctor, when, at 3am, he made the error.

It involved two indentical looking liquids, contained in almost identical bottles.

One was saline solution, the other potassium chloride.

Saline is an everyday tool in the health service, used to dilute far more powerful medications like potassium chloride.

I was tired, and I was too naive and not brave enough to ask for help

Dr Phil Hammond

He told the BBC: "I was working a locum shift, which I had never really been trained to do.

"I was called to see a woman at 3am, and was asked to give her a small amount of potassium in a drip.

"I was tired, and I was too naive and not brave enough to ask for help."

Instead of a bottle of saline, he picked up the almost identical bottle of potassium, and hooked it up to her drip.

Fatal dose

At that dose, the drug would have stopped the patient's heart within moments.

Drug danger: Confusion can cause mistakes

"If the drip had been in properly, I would have killed her.

"Fortunately I was so incompetent that I hadn't even done that properly."

Instead, the small amount of potassium which reached the small area around the needle caused intense pain to the patient.

"I realised straight away, but I didn't admit what had happened, I made some fatuous comment that she must be allergic to saline.

"It was a very near miss."

You just burn the notes, bury the x-rays and push it under the carpet

Dr Phil Hammond

Regulations brought in by the government last year now demand that all "near misses" - especially a close call like this - should be reported to management, and ultimately to the National Patient Safety Agency so that lessons could be learned.

No-one told

That wasn't the case then.

"I didn't report it. There wasn't any error reporting system."

He said that the climate of the times meant that doctors were too ashamed to own up to any error, and he told only a few friends.

It's exactly the same as pushing the wrong number into a cash machine, putting a video back in the wrong box.

Dr Phil Hammond

"You just burn the notes, bury the x-rays and push it under the carpet."

And his mistake was no isolated incident.

"Most doctors in training can remember situations where they either directly led to the demise of a patient or a very near miss, often through drug maladministration, with lots of drugs with very similar names, lots of similar bottles."

"When you analyse it, it's exactly the same as pushing the wrong number into a cash machine, putting a video back in the wrong box. They are ordinary, everyday errors."

He fully supports a move to a "no-blame" culture, which recognises that "good people can make bad mistakes", as this will help bring in changes to keep patients safer.

"We shouldn't have to wait for a hundred deaths to change the colour of a bottle."