Professor Carol Fitzgibbon of the Newcastle University school of education accused the Office for Standards in Education of littering its reports with "ill-founded anecdotal comments based on inadequate evidence and often no evidence at all."
She dismissed the label of "failing schools" as "a vicious notion" which tarnished everyone regardless and had "a devastating effect on the lives of everyone - parents, pupils and teachers. I cannot forgive their mental cruelty and public humiliation of teachers," she said.
Professor Fitzgibbon's work is highly respected in Government circles. The value-added report from the Department for Education this week draws substantially on her thinking.
She was also recently awarded the three-year contract from the School Curriculum and Assessment Authority to research more thoroughly ways of measuring the value added by schools.
"We need new styles of long-term evidence-based research on which we can make valid judgments in education, she told the Sixth Form Colleges' Association conference.
She damned OFSTED as epitomising all that was wrong with the present approach to education and urged its chief executive Chris Woodhead to look to the Further Education Funding Council for a model of good practice.
"Do we really pay Pounds 30,000 for statements like: 'The school promotes satisfactorily the social and moral development of pupils but not their spiritual and cultural development'? We need clear evidence of what works, not just words."