The parents of two of Lucy Letby’s victims have called for a public inquiry into why the nurse’s attack spree was not stopped earlier.

The couple said they felt “very, very let down” by bosses at the Countess of Chester Hospital who were first made aware of concerns over Letby after the deaths of three infants in a fortnight in June 2015.

Ten months later, Letby attacked their newborn twin sons on the same day shift on April 9 2016 when she poisoned Child L with insulin and later injected air into his brother, Child M.

The boys’ father said: “There’s no way she should have been able to get away with it for so long.”

Child M made a sudden “miracle” recovery following no spontaneous response to six doses of adrenaline over 30 minutes, the trial at Manchester Crown Court heard. His twin also survived.

But the parents were unaware Child L had received unprescribed insulin as hospital medics failed to inform them.

They said they were “shocked” to learn two years later from investigating police that their son had experienced low blood sugar readings for more than 48 hours and that a lab result revealed insulin in his system was not naturally occurring.

A similar lab result for another of Letby’s infant victims, Child F, was also not passed on to his parents in August 2015 and his twin brother, Child E, was also, fatally, injected with air.

The father of L and M said he and his wife were “ecstatic” when the boys were born.

He said: “Saturday April 9, we had come down with my parents to see the boys. Everything was going well. They held the boys.

“We went back upstairs because my wife was in the ward upstairs and then within 10, 15 minutes a nurse is coming charging upstairs saying you need to come back down. And I was there first because my wife was still in bed.

“The image that I saw was just horrendous. That image I’ll never forget because it’s on the brain. I saw doctors around the trolley. And they were just pumping his heart. He (Child M) was just like a ragdoll really.

“I was in floods of tears. I just didn’t know what to think. We were first-time parents, we didn’t know what was going on.

“They were prescribing medication and they were ready to give up. (Consultant) Dr (Ravi) Jayaram was ready to give up after 30 minutes, and then all of a sudden (Child M) just came back to life out of nowhere.

“Dr Jayaram is my hero. He saved our son and without his expertise and professionalism I don’t know where I would be today.

“The doctors told us this kind of thing happens in premature babies… and at that time we believed what they were telling us because we didn’t know any different.

(“Child M) had the collapse at 4 o’clock but we didn’t know about (Child L). We didn’t know. Full stop. We didn’t know. We only knew when the police came.

“We were shocked because the hospital had not told us. Not insulin or blood sugars, we didn’t know anything about that.”

The boys’ mother said: “My legs were so shaking, I sat down on the floor and just cried. They told us about (Child L) and we didn’t know anything.

“Every day we rang (the hospital) in the morning and evening (and asked), ‘how is our boys, how is our boys’ and they said doing very well, very well. Every single day up until they were discharged on May 3.”

Both parents thought the hospital should have removed Letby from the unit earlier than July 2016.

The boys’ mother said: “Why did they wait until 2016? As soon as two or three babies died, why wait until 17 babies (were harmed)? I blame them as well.”

Her husband said: “If they’d acted on the initial suspicions, then definitely, they could have stopped any more babies being attacked.

“It would have prevented multiple deaths. It didn’t have to be that many. It could have been a couple maybe. Investigations could have started and she would have been off the unit and they would have been able to investigate properly.

“How it could have gone on so long? Why it went on so long? Those are the answers we need.

“Obviously, that’s a different part of the investigation, We will have to wait for the hospital to answer those questions. But it could have been stopped, that’s a fact.”

He said the hospital should have taken action after the August 2015 lab result indicated Child F had inappropriately received manufactured insulin.

He said he felt “very, very let down” and added: “They should have investigated that one and it would never have got to us. They might have stopped it by then. They need to be held accountable.”

Letby’s trial heard that senior consultants who flagged their concerns to management on several occasions were not aware of the insulin lab tests results of Child F and Child L – both ordered by other doctors on the unit.

Asked whether there should be an independent inquiry, the boys’ father said: “Yes, definitely. A public inquiry.

“The higher management, they need to be held accountable. The doctors raised their concerns and they didn’t act upon them. They dismissed them and it could have been prevented.”

He said that a scan had showed that one part of Child M’s brain had been damaged permanently.

He said: “He may deviate from his peers. At the moment if you look at him he’s just like a normal child, so it’s just something we’ll have to keep monitoring as the years progress.”

The boys’ mother said: “I love my kids too much. Even when they’re arguing or fighting. They are my life.

“When we heard what Lucy did to our kids, we broke down. Previously, we were very happy. We tried to say to them that Lucy has tried to harm you. But they don’t understand.

“They make a joke, ‘we will kick her, we will bite her, we will pull her hair, mummy’. They don’t understand yet.”

Her husband said: “Obviously, we’ll speak to them again when they are a bit older, when they can understand. But it’s important that they know this happened to them and they don’t hear it from a third party or something.”

Asked for his thoughts on Letby, he replied: “She means nothing. Just an evil person. There’s no way she should have been able to get away with it for so long.”

The boys’ mother added: “She already proved her note, ‘I am evil, I did it’.”