for armed robbery, John Irvine and Keith Twitchell, whose convictions were also later quashed. 1980s and declining performance By 1982, the number of arrests by SCS had declined to less than 200. Despite a steady increase in reported crime and arrests made in the West Midlands, the squad generally reported fewer than 200 arrests a year during the 1980s. As a percentage of arrests made by West Midlands Police as a whole, their work was declining. Furthermore, many of the arrests were in practice for less than serious crimes. Burglary and theft accounted for around half of the arrests made. Explanations put forward included that criminals were becoming more sophisticated and were less "amenable" to making confessions. In 1988, the West Midlands Police explained that "Investigations are more protracted, and masks, disguises, false number plates and other means of evading capture are frequently used", techniques which are hardly unusual among hardened criminals committing serious crimes. Kaye concludes that police management knew that these excuses were thin, and that the squad was underperforming throughout the 1980s. In 1984, the squad began to rely heavily on 'supergrass' evidence. These later proved unreliable, but did lead to a number of high-profile arrests. By the mid 1980s, colleagues "resented the 'support'" of the squad, thus avoided collaboration and referrals, further reducing the squad's ability to pursue serious crime. The District Auditor strongly criticised the organisation's poor management in 1985 and 1989. The West Midlands police claimed that the SCS was being reorganised in 1988, with changes to recruitment practices, just before it was closed down. The Police and Criminal Evidence Act 1984 should have changed many practices at the SCS, for instance by introducing the recording of interviews, and was noted as implemented in the 1986 annual report. Subsequent evidence however shows that its provisions were being widely ignored or evaded. Rising concerns Throughout the 1980s, there were concerns about the safety of the Birmingham Six convictions. Chris Mullin campaigned as an MP to see their convictions reviewed. Concerns about the Bridgewater Four, who had been investigated by the sister No 4 Regional Crime Squad, were investigated by Paul Foot. A number of cases had been overturned in the 1980s and several members of the squad were seen to be unreliable witnesses. However, concerns were given particular credence due to a new forensic technique, using a machine known as an ESDA, or Electrostatic Detection