A doctor who provided crucial expert testimony in the prosecution of Lucy Letby, the nurse convicted of murdering and attempting to murder babies at the Countess of Chester hospital, was under investigation by the medical regulator at the time he gave evidence. The General Medical Council (GMC) launched an investigation into Prof. Peter Hindmarsh on November 25, 2022 – the same day he first appeared as a witness in the trial.
The investigation, prompted by concerns raised by University College London hospitals trust (UCLH) and Great Ormond Street hospital, centered on allegations of harm to patients, inappropriate diagnoses and treatments, and inadequate documentation, according to documents obtained by The Guardian. A medical tribunal subsequently imposed restrictions on Hindmarsh’s practice, stating he “may pose a real risk” to the public, though it permitted him to continue providing expert witness testimony in the Letby case.
The jury was not informed of the GMC investigation or the restrictions placed on Hindmarsh. The Crown Prosecution Service (CPS) informed the defence it would oppose any attempt to disclose the investigation, arguing the allegations hadn’t reached a final adjudication. Hindmarsh ultimately removed himself from the GMC register in November 2024, effectively ending the investigation without a regulatory finding against him.
Hindmarsh, a professor and consultant paediatric endocrinologist, testified that two babies, referred to as F and L, had been poisoned with insulin. His evidence was central to the prosecution’s case, which alleged Letby deliberately administered insulin to these infants. He had been an honorary consultant at Great Ormond Street hospital, but his contract was terminated four months before he began his testimony, in July 2022. Great Ormond Street declined to comment on whether the termination was related to the allegations that led to the GMC investigation.
During his initial court appearance on November 25, 2022, Hindmarsh confirmed he was a consultant at UCLH and stated he was also an honorary consultant at Great Ormond Street, without clarifying that his contract there had ended. The jury was not informed of the ongoing investigations into his practice.
UCLH formally investigated Hindmarsh, and on November 15, 2022, Great Ormond Street referred “multiple and wide-ranging concerns” about his practice to the GMC. The regulator opened its formal investigation ten days later. Further concerns were raised by UCLH on December 21, 2022, leading to Hindmarsh’s suspension pending a return to work under “close supervision.”
The allegations against Hindmarsh included “identified cases where harm to patients has been alleged,” as well as concerns about his “diagnosis and treatment of patients,” “utilize of treatments in unusual age groups, without adequate monitoring,” and “inappropriate investigations.” By January 2023, the tribunal had renewed restrictions on his practice, citing a “real risk” to the public due to the “number and nature of the concerns.”
Despite these concerns, the tribunal allowed Hindmarsh to continue working as an expert witness, provided he disclosed the GMC investigation to any party instructing him – a requirement already mandated by criminal procedure rules. A source familiar with the prosecution stated the CPS was not informed of the UCLH-led investigation until December 2022, after Hindmarsh’s first testimony.
Hindmarsh formally informed police of the GMC investigation on December 14, 2022. The CPS disclosed the investigation to Letby’s defence counsel four days before Hindmarsh’s second day of testimony. The prosecution opposed informing the jury, maintaining the allegations hadn’t been finalized.
Letby was convicted of murdering seven babies and attempting to murder seven others following two trials concluding in 2024. She has maintained her innocence, and her supporters contend she was scapegoated for systemic failings within the neonatal unit. Dozens of medical and scientific experts have since argued the prosecution’s medical case, including Hindmarsh’s evidence, was flawed. A 14-member expert panel led by Dr. Shoo Lee concluded unanimously that the babies died or collapsed due to natural causes and inadequate care, finding no evidence of murder or deliberate harm.
Letby’s lawyer, Mark McDonald, applied to the Criminal Cases Review Commission (CCRC) in February 2024 to have her case reviewed, supported by reports from 27 experts, including Lee’s panel. The CCRC is currently reviewing the application.
Hindmarsh made his second appearance at the Letby trial on February 24, 2023, with the jury remaining unaware of the investigations and restrictions surrounding his practice. His evidence regarding insulin poisoning was described by the prosecution as “incontrovertible.” Experts now challenging Letby’s convictions have contested Hindmarsh’s insulin evidence, citing concerns about the reliability of the tests used and the plausibility of the prosecution’s theory.
A spokesperson for Hindmarsh stated he had “no comment to make.” A GMC spokesperson confirmed Hindmarsh relinquished his registration on November 14, 2024.
