Thirlwall report lands as Letby's scientific camp splits

The Thirlwall Inquiry is due to publish its final report on 15 September into how Lucy Letby was able to murder and harm babies on the neonatal unit at the Countess of Chester Hospital. Letby, 36, is serving 15 whole-life terms for murdering seven infants and attempting to murder seven others, including one baby she was convicted of trying to kill twice, between June 2015 and June 2016. A later retrial added a further attempted murder. The inquiry was not asked to retry her. It was asked to examine the hospital, the trust board, managers, doctors, nurses and the wider NHS from her arrival in 2012.

Lady Justice Kathryn Thirlwall heard six months of evidence at Liverpool Town Hall between September 2024 and February 2025. Parents of the dead and injured children gave evidence. The inquiry cost more than 18.5 million pounds and reviewed thousands of documents. Thirlwall has said it was utterly unacceptable that a similar crime could follow the Beverley Allitt murders in Grantham a generation earlier, after an inquiry into that case had already been held. She refused a request last year to pause her work while others attacked the convictions. She called that debate noise that added to the families' distress and said criticism of the verdicts sat outside her terms.

The report is expected to describe missed chances to act, including after three babies died in quick succession in June 2015, and to recommend changes in how NHS managers handle staff about whom doctors raise alarms. The Crown Prosecution Service said earlier this year that it did not have enough evidence for further charges linked to Letby's work at Chester or at Liverpool Women's Hospital.

The publication lands inside a second, unfinished argument. The Criminal Cases Review Commission has been examining a dossier submitted on Letby's behalf for about 18 months. The commission has said it will read the Thirlwall report closely. On 14 September two experts left the defence-adjacent scientific effort. Helen Shannon, a chemical engineer, and Geoff Chase, a bioengineering professor in New Zealand, had produced a 100-page report last year that questioned the insulin-poisoning convictions of two babies. They told The Guardian they still regard those two convictions as carrying a very strong level of reasonable doubt, but that some arguments now being advanced for Letby were inconsistent with the available evidence, science and established physiology.

That split matters because the insulin cases were central to the prosecution's story of deliberate harm. If specialists who doubt those two verdicts also reject other parts of the innocence campaign, the CCRC is left with a narrower scientific file than campaigners have claimed in public. If Thirlwall finds that the neonatal unit was understaffed, poorly governed or slow to isolate Letby, campaigners will treat those findings as evidence that deaths were misread. Thirlwall has already said her job is the institution, not the jury.

The families who sat through the criminal trials and then through Liverpool Town Hall are the people for whom both processes were built. They were told the nurse killed their children. They were then asked to relive the ward's delays so that the next board in the next hospital might move faster. A report that names managers and dates will be some of what they were promised. A report that is immediately mined for appeal points will feel like a second trial conducted in public without them.

NHS neonatal care is a system of scarce cots, rotating juniors and consultants who must decide when a cluster of deaths is a crime and when it is a failing unit. Allitt and Letby, twenty-five years apart, are the two names that make that decision unbearable and obligatory. Thirlwall's pages will be read as a manual for the next cluster. They will also be read, against her stated scope, as a commentary on a conviction that a growing group of doctors and statisticians have spent two years trying to reopen.

The document appears on Tuesday. The CCRC remains the only body that can send the case back to the Court of Appeal. Until it does, or declines to, Letby stays in prison under whole-life orders, and the Countess of Chester stays the hospital where seven babies were found to have been murdered. Those are the legal facts the report cannot change. What it can change is how the next consultant's letter about a colleague is handled on a Monday morning.