Step 1: the CCRC decides
The CCRC, having received the October 2025 application and the thirty-one-plus independent expert reports, will consider whether the statutory “real possibility” test under section 13 of the Criminal Appeal Act 1995 is met. That is a lower bar than probability. The CCRC has no statutory deadline; comparable- complexity applications typically take between 18 months and several years.
If it refers, the matter goes to the Court of Appeal (Criminal Division). Referral itself does not overturn anything; it triggers a fresh hearing.
Step 2: the Court of Appeal hearing convenes
A Court of Appeal hearing following a CCRC referral is typically heard by three Lord or Lady Justices of Appeal. The hearing is a procedural one: the Court receives written skeleton arguments, oral submissions, and potentially live expert evidence on the new material. The Court does not re-try the case in the Crown Court sense. It examines whether, in the light of the material now before it, the convictions are safe.
The evidential burden on referral
At the Court of Appeal, the question is not whether guilt has been proved beyond reasonable doubt. That question was answered by the 2023 jury. The Court’s question is whether the convictions are safe in the light of the new evidence. A conviction is unsafe if, for example:
- The jury heard fundamentally unsound expert evidence.
- Material evidence was not before the jury that would have made a real difference.
- The judicial direction was inadequate in a specific, identifiable way.
- A procedural irregularity undermined the fairness of the trial.
The Letby CCRC application relies primarily on the first two: new expert evidence that the jury did not have, and methodologically unsound expert evidence that it did have.
Step 3: the possible outcomes
- Convictions quashed, no retrial. The most complete outcome. The Court of Appeal finds the convictions unsafe and does not consider a retrial viable on the evidence now available. The defendant is released (subject to any other custodial sentences).
- Convictions quashed, retrial ordered. The Court of Appeal finds the convictions unsafe but considers a properly-conducted retrial is possible. The defendant goes to a new Crown Court trial with the new evidence available.
- Some convictions quashed, others upheld. The Court of Appeal finds some counts unsafe but upholds others. This is possible because the medical-evidence concerns are stronger on some counts than others.
- Convictions upheld. The Court of Appeal finds that, even on the new evidence, the original convictions remain safe. This does not preclude a further appeal to the Supreme Court or a further CCRC application on new material.
What a retrial would look like
If a retrial is ordered, the case would be tried again in the Crown Court. The jury would hear the new expert evidence — the Panel report, the Joint Insulin Report, the statistical reports, the paediatric-pathology re-readings — alongside whatever the Crown chose to adduce in rebuttal. The case would, in practical terms, be a different case from the 2022–2023 trial.
A retrial is not a guarantee of acquittal; it is a guarantee of a fresh evidentiary hearing. But on the evidence now in the public domain, many independent commentators (Rinder KC, Davis MP, Sumption, the Bar Council signatories) believe a retrial on the current body of evidence is unlikely to produce the same result as the 2023 trial.
The two sets of convictions
There are two separate sets of convictions: the 2023 convictions from the original trial, and the 2024 conviction from the Child K retrial. They would typically be considered together on CCRC referral, because the methodological and evidential concerns affect both. The October 2025 McDonald KC application addresses both.
Timescales
Typical timescale from CCRC referral to Court of Appeal judgment:
- CCRC referral decision: months to years after application (October 2025 filing).
- Listing at Court of Appeal: several months after referral.
- Preparation, skeleton arguments, service of expert evidence: several more months.
- Hearing itself: typically 1–5 days for complex expert-evidence cases.
- Judgment: typically reserved and handed down weeks to months later.
Realistic total: 2 to 4 years from CCRC application filing to Court of Appeal judgment. The Post Office Horizon parallel is instructive: from the 2019 High Court Bates judgment, the first Court of Appeal quashings took until December 2020.
Why understanding this procedure matters
Public engagement with the case is sometimes dismissed on the grounds that “the courts have decided”. That framing misreads the procedural architecture. The courts have decided on the evidence of 2023. The CCRC and potentially the Court of Appeal will decide, next, on the evidence of 2025 and 2026. The two are different decisions on different evidence. A defendant entitled to the second decision is not foreclosed by the first.