Cheshire police and the Crown Prosecution Service say Professor Peter Hindmarsh did not tell them about a hospital investigation into his medical work before he first gave expert evidence in the Lucy Letby trial. The omission raises a serious disclosure question, but it does not by itself establish that his trial evidence was wrong or that any conviction will be overturned.
The Guardian reported on March 11, 2026, that University College London Hospitals NHS Foundation Trust was leading a formal investigation into multiple concerns, with involvement from Great Ormond Street Hospital, before Hindmarsh appeared at Chester Crown Court. A representative for Hindmarsh declined to comment.
What Police and Prosecutors Say Was Not Disclosed
Hindmarsh was a consultant paediatric endocrinologist at UCLH and an honorary consultant at Great Ormond Street. The Guardian reported that Great Ormond Street terminated his honorary contract in July 2022, four months before his first appearance as an expert witness. Cheshire police said he had not disclosed that termination to the force.
The hospital inquiry and the later regulatory process must be kept distinct. Great Ormond Street referred concerns to the General Medical Council, which opened a fitness-to-practise investigation on November 25, 2022, the day Hindmarsh first testified. The hospital informed him five days later. Police and the CPS said his first disclosure came on December 14, when he told police about the GMC investigation.
The jury was not told about either investigation. The Guardian reported that allegations against Hindmarsh were never finally adjudicated because he voluntarily left the medical register in November 2024. That outcome is not a finding that the allegations were proved.
Two barristers consulted by the Guardian said an expert would generally be expected to reveal an employer investigation that could affect competence or credibility so its relevance could be assessed. Tim Green KC framed the point conditionally: an adverse report about competence or skill would be information he expected an experienced medical expert to disclose to the instructing lawyers.
Hindmarsh's Evidence Concerned Two Insulin Cases
Hindmarsh gave evidence about the prosecution's allegation that synthetic insulin had been added to fluid bags used for Child F and Child L. The Court of Appeal's 2024 judgment records his opinion that blood results in Child F showed exogenous insulin administered over about 17 hours and that more than one bag had been contaminated. For Child L, he said the prolonged hypoglycaemia could only have been induced by insulin in the feed.
The same judgment records an important limit on the dispute at that appeal: Letby accepted at trial that both babies had been poisoned with insulin but denied being the person who poisoned them. The prosecution relied on Hindmarsh's interpretation alongside circumstantial evidence when arguing that the same person was responsible for both episodes.
The insulin allegations mattered. The Guardian described those verdicts as two of only three on which the original jury was unanimous. Letby was convicted across two trials of murdering seven babies and attempting to murder seven others at the Countess of Chester Hospital. She maintains her innocence.
None of those facts makes a credibility issue immaterial. Cross-examination is how a jury tests an expert's qualifications, assumptions and reliability. Information about an investigation or terminated hospital contract could have allowed the prosecution to assess its disclosure obligations and the defence to ask whether the concerns bore on the insulin opinions. That connection requires evidence, not inference from the existence of the inquiries.
The Disclosure Rules Require a Careful Assessment
CPS guidance says an expert's overriding duty is to assist the court with objective and unbiased opinion. It also says experts have disclosure obligations under the Criminal Procedure Rules and that material bearing on an expert's competence or credibility is relevant to an investigation and may need to be disclosed in later proceedings.
That guidance does not support the old article's categorical claim that every employer investigation automatically creates a successful appeal. It explains that failures can have consequences, including an appellate court finding a conviction unsafe, but that is a possible result after legal assessment. The nature of the concern, what the expert knew and whether it could have affected the evidence all matter.
The distinction matters because the hospital allegations were not adjudicated. A fair account cannot treat them as proof that Hindmarsh's endocrinology analysis was unreliable. It also cannot dismiss nondisclosure as irrelevant before an independent authority has examined the material. Both shortcuts replace the legal test with a preferred conclusion.
Letby's lawyer, Mark McDonald, told the Guardian he would submit the nondisclosure as further evidence in an application already before the Criminal Cases Review Commission. The CCRC review is the route through which the new material can be assessed for a possible referral to the Court of Appeal. At the time of the report, the commission had not announced that this issue made the convictions unsafe.
The Missing Disclosure Needs an Independent Answer
The defensible criticism is direct. Police and prosecutors say they were not told about the UCLH-led inquiry before Hindmarsh testified, even though the CPS expects potential competence and credibility material to be revealed and assessed. Leaving that information outside the trial process denied the parties and court a timely decision on its relevance.
Accountability requires more than accusing Hindmarsh of concealment or declaring the insulin evidence destroyed. Reviewing bodies should establish the scope and findings of the hospital work, the date and content of every disclosure, what each legal team knew and any connection between the concerns and his opinions about Child F and Child L.
If the material had no bearing on those opinions, an independent record can explain why. If it could have assisted the defence or undermined the prosecution case, the legal system has procedures for disclosure review and a possible appellate referral. The answer cannot be supplied by a headline that assigns intent before the evidence is tested.
Expert evidence carries unusual authority because jurors rely on specialists to explain technical material they cannot evaluate unaided. That authority demands a disclosure system stronger than self-reporting followed by argument years later. The hard conclusion is not that the verdicts have collapsed. It is that a credibility question capable of examination before trial was left unresolved, and the justice system now has to examine it in public and on evidence.