Yet another crucial development has emerged in the Lucy Letby case, raising fresh questions about the evidence given by Dr Ravi Jayaram. Let me explain what happened, and when.

During Miss Letby's first trial in 2022, the prosecution relied on electronic door-swipe records to show which members of staff came in and out of the neonatal unit, and when. The prosecution was later forced to admit that records for one of the doors had been misrepresented at the trial. Events recorded as staff 'leaving' the neonatal unit were actually staff 'arriving' onto the unit, and those recorded as 'arriving' were actually 'leaving'. That matters. The swipe data was used to establish which nurses were where at given points in time. The data was therefore vital to the prosecution's case.

Because, if the timeline relied upon by the prosecution was based on incorrectly labelled data, it could have important implications for individual allegations, as was the case with the allegation concerning Baby K, for which Miss Letby was re-tried in 2024. At the first trial, the prosecution claimed that Jayaram found Lucy Letby standing by Baby K's incubator as the baby deteriorated at 3.50am on 17 February 2016. Crucially they claimed the door-swipe records showed that Baby K's designated nurse, Joanne Williams, had left the intensive care unit at 3.47am. But this was wrong. The swipe data, corrected for the retrial in 2024, instead indicated that Joanne Williams had actually returned to the unit at 3.47am. This meant Lucy Letby was not alone with Baby K when they deteriorated in the way originally suggested.

I therefore wrote to Sarah Hammond, Chief Crown Prosecutor of Mersey-Cheshire CPS, in August 2024, asking for clarification about the errors in the door-swipe evidence presented during the first trial.

In her response, Sarah Hammond described this as "not [having] a significant impact” upon her convictions. Frankly I find this an extraordinary claim.

After Cheshire Police realised the swipe data used at the first trial had been presented the wrong way round, they interviewed Dr Ravi Jayaram again. Crucially, this interview took place before Miss Letby's retrial in 2024. During that interview, the officer said to Jayaram: "We can't change the data... But we can change the interpretation of it." Jayaram, upon being confronted with the errors in the swipe data, abandoned the precise timings he had previously given, citing the difficulties of "retrospective documentation".