The Guildford / Royal Surrey laboratory — the UK forensic-insulin standard
Prosecution claim
The Crown's insulin evidence was produced by the Royal Liverpool clinical biochemistry laboratory using the Roche Cobas screening immunoassay. This laboratory and protocol was treated at trial as adequate for the forensic weight placed on the result.
Counter-evidence
The UK forensic standard for insulin assay in criminal cases is the Royal Surrey County Hospital (RSCH) laboratory at Guildford. Guildford is the reference laboratory accredited under the Forensic Science Regulator's code of practice for endocrinology work in criminal proceedings. It operates mass-spectrometry confirmatory testing alongside the screening immunoassay, at forensic-grade chain-of-custody standards, with protocols fit for forensic purpose. Royal Liverpool is a clinical biochemistry laboratory — competent for clinical diagnostic work, but not operating under the Forensic Science Regulator's code of practice for criminal-evidence purposes. Sending the Countess of Chester samples to Royal Liverpool instead of Guildford was a forensic chain-of-custody failure: the clinical laboratory's protocol is not designed to produce evidence that can bear criminal-trial evidential weight.
A clinical-biochemistry screening result is not a forensic result. Forensic insulin results in the UK come from Guildford. Clinical results come from hospital laboratories. The chain-of-custody distinction matters because the protocols are not the same.
What the jury heard
The jury heard the Royal Liverpool result treated as authoritative. The Forensic Science Regulator's code of practice and the distinction between clinical and forensic laboratories were not a central feature of the Crown's case.
What the Panel says
The Joint Expert Witness Insulin Report (May 2025) sets out, in technical detail, why the screening result produced by the Royal Liverpool clinical biochemistry laboratory cannot bear the evidential weight the trial placed on it. Forensic-standard testing (Guildford / mass-spectrometry confirmatory protocol) was not performed.
What independent experts add
- The Forensic Science Regulator is a statutory body; its code of practice sets UK-wide standards for laboratories producing evidence for criminal proceedings.
- Guildford (RSCH) operates under that code of practice for endocrinology work.
- Royal Liverpool clinical biochemistry does not operate under that code of practice — it is a clinical diagnostic laboratory.
- The distinction is not academic: clinical-lab chain-of-custody, sample-handling protocols, and validation documentation are designed for clinical-diagnostic purposes, not for criminal-trial evidential purposes.
- Sending samples to Liverpool rather than Guildford was a decision made at the investigative stage; it shaped every subsequent evidential step.
- The 2010 Liverpool protocol in force at the time of testing did not state the laboratory could not diagnose exogenous insulin; the 2012 protocol did.
- No confirmatory mass-spectrometry testing was performed. This is the single fact the forensic standard requires and that the trial record lacks.
- Comparable UK insulin-based convictions (notably Colin Norris) have subsequently come under CCRC scrutiny on related evidential standards.