Semtex traces may have been on forensic machine since 1989
It would never happen again, the British government pledged. As the Birmingham Six, quickly followed by Judith Ward, all walked free after years of imprisonment on the basis of seriously-flawed scientific evidence, the then Home Secretary immediately established a Royal Commission to investigate what was wrong with the judicial system.
One of the commission's key recommendations to prevent further miscarriages of justice was the establishment of an independent Forensic Science Advisory Council. This proposal was immediately endorsed by the legal establishment because it was felt competition between government and private laboratories had led to "cost pressures" which threatened standards.
Although the then Lord Chief Justice, Lord Taylor, described the proposal as "one of the single most important recommendations", the British Home Secretary, Mr Michael Howard, failed to act.
Instead the Ministry of Defence's Royal Armament Research and Development Establishment (RARDE), which was involved in the flawed testing of samples that wrongly convicted the Maguire family and Judith Ward, moved to Fort Halstead, near Sevenoaks, Kent, and was left to regulate itself.
The contamination of the Forensic Explosives Laboratory's centrifuge, used in tests for explosives to separate dirt from the materials under analysis, was only discovered by accident when a scientist spilt some liquid but kept on getting "positive results" for explosives after he had cleaned it up.
An investigation into the source of the contamination pinpointed a rubber bung, costing only a few pence to replace, on the centrifuge. The laboratory was forced to admit that the traces of Semtex on the equipment could possibly have been there since 1989 when the machine was installed.
Worse still, it emerged that this vital piece of equipment was second-hand, brought from another laboratory, and had never been tested for contamination over the seven-year period. Staff had not even thought to replace the metal tubes or rubber bungs - the same ones were used for 500 tests carried out since 1989.
The laboratory notified Mr Howard in May about the implications of this contamination as it clearly called into question the forensic evidence in many high-profile cases, many of them IRA cases.
Among those convicted IRA prisoners who immediately lodged appeals after these revelations were Sean McNulty (25), who was jailed for 25 years in 1994 for blowing up gas and oil works on north Tyneside; Nick Mullen, jailed for 30 years after police discovered Semtex at his home; and Hugh Jack (37), jailed for 20 years for conspiracy to cause explosions. In a statement to the Commons, Mr Howard admitted there was a "small theoretical possibility" that case samples might have been contaminated and appointed Prof Brian Caddy, of Strathclyde University, to examine all the necessary paperwork and assess whether the evidence might be tainted.
It was a shrewd appointment. Campaigners will have problems criticising Prof Caddy's conclusions as he is one of Britain's leading forensic scientists and a veteran of miscarriage-of-justice cases. In 1985 he became the first scientist publicly to question the validity of the alleged forensic evidence against three of the Birmingham Six.
During their second successful appeal, Prof Caddy testified on their behalf and explained how the evidence could have been contaminated by soap. He was also the forensic adviser to the Maguire family during Sir John May's inquiry into the convictions of the Guildford Four.