They are known as “car park” teams because that’s where the inspectors first meet, says the study directed by academics at Keele and Brunel universities.

The authors, professors Maurice Kogan of Brunel and Margaret Maden, suggest that widespread complaints about the lack of consistency across school inspections is partly due to the reliance on contractors.

The study commissioned by the Office for Standards in Inspection (OFSTIN), an anti-OFSTED pressure group, is the most extensive attempt so far to gauge schools’, parents’ and policy-makers’ views of the inspection service, notwithstanding the two other surveys reported this week.

OFSTIN said that the most common complaint was teams’ varied qualifications and experience.

The report says some teams “display the characteristics of jobbing builders”. It adds: “Staff in schools rapidly become aware that teams, commonly referred to as ‘car park teams’, had not worked together or even met prior to the inspection.”

In schools this led to “a lack of credibility in the inspection team, and, more importantly in their ability to make standardised judgments about teaching quality both between and within schools.”

The research team led by Sandra Jones and Valerie Beale and conducted by Brunel and the Helix Consulting Group questioned more than 2,000 schools in England; carried out case studies in 26 schools and talked to government agencies, teacher unions and governors’ organisations.

The report concludes that there is a case for a permanent cadre of school inspectors. It says: “It seems unlikely that the problems of credibility will ever be solved while inspection is in the hands of more than 16,000 registered, team and lay inspectors.”

The researchers conclude that it would be “hazardous” to assume any connection between OFSTED inspection and improved performance from schools.

News, 6; Leader, 18: Analysis, 27