Why he matters in this case
Prof. Richard Gill is one of the people most responsible for the fact that the statistical case against Lucy Letby is now, in the public sphere, widely regarded as unsound. He does not speak for a campaign. He speaks for a discipline. And he has done this before.
The Lucia de Berk precedent (2003–2010)
In 2003, Dutch paediatric nurse Lucia de Berk was convicted of seven murders and three attempted murders on the basis of a similar-looking statistical pattern — her apparent presence at an improbable number of unexpected events. Prof. Gill worked with Dutch statisticians and lawyers to demonstrate, in detail, that the statistical argument was a selection-bias artefact. In 2010, the Dutch Supreme Court overturned her conviction.
The de Berk case is now a textbook teaching example in European statistics and law-and-science courses. It is frequently cited alongside the R v Clark cot-death case in the UK as the canonical modern example of a conviction overturned on statistical grounds.
What he says about Letby
Since the Letby convictions in 2023, Prof. Gill has published letters, talks, and lecture transcripts arguing that the statistical structure of the Letby case is the same as de Berk’s. The 2024 lecture “A tale of two Lucies”, hosted at lucyletby.org, walks through the parallel explicitly.
His specific point is that the shift-rota chart shown to the jury is a definitional consequence of how the “suspicious events” were identified — selected, in part, because Ms Letby was present — rather than evidence that her presence is improbable. See our shift-chart evidence page and our statistics deep-dive.
Professional background
- Emeritus Professor of Mathematical Statistics, Leiden University.
- Past president of the Netherlands Society for Statistics and Operations Research (VVSOR).
- Author of published work on statistical evidence in criminal trials, medical statistics, and survival analysis.
- Known publicly for his role in the Lucia de Berk exoneration, on which he has lectured internationally.
Why his position is weight-bearing
Prof. Gill is not an activist. He is a senior academic statistician who has spent most of his career inside the discipline’s formal channels. His willingness to speak publicly about a case is itself a signal that something has gone wrong at the level of statistical methodology that the discipline considers non-negotiable.
That is the same signal that carried weight at the Dutch Supreme Court in the de Berk case. It does not, by itself, decide the Letby case. It is not meant to. What it does is make it implausible to characterise the statistical critique as fringe.