Only 25 inspectors have been de-registered during a period when 25,000 schools have been inspected - a fact which OFSTED says reflects well on the majority.
The case of Geoffrey Owen, the inspector now the subject of an internal inquiry by the Office for Standards in Education, has set alarm bells ringing about the way in which a few inspections are conducted.
In the past year OFSTED has had 230 complaints, mainly from schools, representing about three per cent of inspections.
Schools not happy with the way OFSTED has dealt with their complaints can have them referred to Elaine Rassaby, the adjudicator appointed in July. So far, she has had only two cases to deal with, though there about 40 cases in the OFSTED pipeline.
OFSTED's registrar, Malcolm Westbrook, says that where an inspector's conduct is at issue, complaints are notoriously difficult to resolve because there are usually conflicting accounts.
Where it appears the inspector has not complied with the code of conduct or has been responsible for a team that has produced an inadequate report, the registrar will recommend to Chris Woodhead, the chief inspector, that the lead inspector be removed from the list of registered inspectors.
A registered inspector has 28 days in which to appeal and there is provision for a hearing with an independent panel. No case has ever reached that stage.
There is no centrally-held list of the far larger number of inspectors (about 9,000) who are qualified to be members of a team. The contractors who bid to carry out inspection work are expected to employ suitable people.
In the cases where OFSTED accepts the report on a school was not adequate, it is not re-written unless it is deemed to be "seriously misleading". In the five years since the present system was introduced, only four schools have been re-inspected because their original report was considered to be of poor quality. Not every school would volunteer to go through the process a second time.
OFSTED this week insisted that it could not comment on Mr Owen further than saying that a complaint had been upheld from a primary school in Bristol. However, Mr Owen is not contracted to carry out any inspections either this term or next.