Lucy Letby’s lawyers argued her convictions should be quashed at an appeal as jurors may not have been certain of her guilt, it can now be reported.

Letby’s legal team unsuccessfully brought a Court of Appeal challenge in April this year over her convictions for the murders of seven babies and the attempted murders of six others.

Reporting restrictions prevented the publication of details of Letby’s arguments at the two-and-a-half-day hearing in London until the end of a retrial at Manchester Crown Court for the attempted murder of a baby girl, known as Child K.

Further details can now be published after the second trial concluded on Tuesday with a guilty verdict.

Letby’s lawyers put forward several arguments in the failed appeal bid, with her barrister, Benjamin Myers KC, arguing that the trial judge, Mr Justice Goss, was wrong to tell the jury they did not need to be sure of the precise act which caused Letby’s victims harm.

Mr Myers said that this was “not correct” as there may have been “other explanations”.

He said: “There may be more counts or all counts where the jury was unable to reach a state of certainty as to guilt.

“They should have been told they should have been sure of the act. They have to have certainty as to the act that lay behind the allegations of deliberate harm.”

Nick Johnson KC, for the prosecution, stated the argument was “not tenable” and that while medical evidence was “at the heart of pretty much all” of the prosecution’s argument, it formed “only part of the circumstances of the case” and that Letby “was always there when things happened”.

He said: “The law does not and has never required the prosecution to prove precise acts or acts were committed to cause death.”

Letby watched proceedings via video-link from a grey room in HMP Bronzefield, Surrey, wearing a cardigan and a dark, spotted top on the first day of her appeal bid.

A second argument was that the judge was wrong not to instruct jurors to disregard evidence from retired consultant paediatrician Dewi Evans.

Mr Myers said that Dr Evans alleged “on the hoof” that certain events occurred and “took the position of an investigator”.

He said: “The manner in which Dr Evans gave evidence, the defence submits that this was extraordinary, emotive, evasive and constructive.”

Mr Myers continued: “If an expert has behaved in the way this expert did, it could not be reasonable to find that their evidence was admissible.”

Mr Johnson called the “reductive” argument an attempt to “isolate and insulate one narrow issue in the case from all the rest of the evidence”.

Mr Myers also argued the judge incorrectly rejected an argument that Letby had “no case to answer” as the prosecution’s evidence “failed to reach the standard” required.

He added that “none” of the medical experts called by the prosecution to give evidence “had any physical experience that could possibly make them experts” in the case.

Mr Johnson told the court that the witnesses were “well-qualified” and that other features of the case helped to prove Letby’s guilt.

He said: “The appellant changing medical records, the appellant always being on shift when these things happened and many other features all, cumulatively and some individually, are well capable of establishing a case for the jury to consider.

“All these cases were against the medical opinion that there was no innocent explanation for the collapse or deaths of these children.”

A further appeal point related to how the judge dealt with a “jury irregularity” after a complaint was made to the court in August 2023.

The Court of Appeal in London heard that the complaint alleged that a juror had discussed the case with members of the public during the trial.

After hearing witness evidence, Mr Justice Goss ruled the juror should continue in their role.

Mr Myers said the verdicts were “imperilled” by the decision, adding: “If there was a member of the jury who was disregarding the directions of the trial judge, which we know is a serious matter, that juror should at the very least have played no further part in the activities of the jury from the moment that these activities came to light.

“It can’t be said that the verdicts that were returned would have been returned.”

But Mr Johnson said the original complaint was not “legitimate”.

He said: “We respectfully submit that looking at all the evidence on that particular issue, (the judge’s decision) was the only reasonable conclusion to draw, and if we are wrong about that, it was a reasonable conclusion to draw.”

Mr Myers also asked the court to consider an argument over new medical evidence, claiming that the information “could have made a significant difference to the evidence presented to the jury”.

Mr Johnson said the “wholly artificial, reductive exercise” would not be allowed at trial and “should not be permitted by this court”.

Dame Victoria Sharp and Lord Justice Holroyde dismissed Letby’s bid in May.

In a 59-page ruling, published on Tuesday after Letby’s conviction, Dame Victoria said the 34-year-old’s appeal complaints were “not arguable” and declined to formally accept proposed fresh evidence.

She added: “In the circumstances of this case, the judge was accordingly correct to direct the jury that they must be sure, on the evidence as a whole, that the applicant had deliberately done something to harm a baby, with the requisite intent for murder or attempted murder, and in the case of those babies who died, that her act or acts had caused or contributed to the death.

“It was not necessary for the prosecution to prove the precise manner in which she had acted.”

The judge also said the trial judge had taken the correct approach when directing jurors and that there was “no arguable basis” for interfering with his decision over the evidence of Dr Evans.