Acompany at the centre of moves to bring private management practices into schools has been failed by inspectors for its maths teacher-training course.
The Office for Standards in Education failed the Centre for British Teachers' two-year distance-learning course - run largely in independent prep schools - because students were not secure enough in their understanding of maths.
Students did not have enough experience of key-stage tests and the levels expected of pupils, or of teaching GCSE and post-16 courses, inspectors said. Assessors tended to give them the benefit of the doubt while mentors in school were often not maths teachers and were unfamiliar with the distance-learning materials.
But CFBT teacher training manager Geraldine Hutchinson said students - recruited by the previous providers of the course - had been marked down for not having maths degrees. They had scored highly in teaching practice and most had been offered jobs eagerly.
Nevertheless, the firm has tightened up recruitment and last year accepted only one student on to the maths course against a target of eight.
The not-for-profit firm is a lead partner in an education action zone, a consultant at a named-and-shamed primary in Hackney, and is competing to take over failing Kings' Manor School in Guildford, Surrey.
It sees the course as an "idiosyncratic and unique" alternative to university teacher education, aimed at mature graduates who want to move into teaching as a second career.
OFSTED's report is a provisional one because the CFBT is a new provider. It failed the maths course in three areas - CFBT's assessment of trainees, trainees' subject knowledge and understanding, and trainees' monitoring and assessment of their pupils.
But, unusually, trainees' planning, teaching and classroom management was rated "good, with no significant weaknesses". CFBT pointed to that result as proof of the success of the course.
As a new provider, CFBT suffers no penalties this time. But all new providers are re-assessed after a year and if it fails again, it can expect a cut in funding and the threat of losing Teacher Training Agency accreditation.
* Two other new providers have been provisionally failed by OFSTED. Harlow-based Essex Primary Training Group, managed by Essex County Council, failed on the quality of its assessment of trainees in English, and on its overall monitoring of quality and standards.
The school-centred South-East Essex Primary Consortium, based at Southend, failed on its assessment of trainees in maths and on trainees' knowledge and understanding of maths.