Douglas Osler was asked to step in by John McFall, the Northern Ireland Education Minister, who is the MP for Dumbarton, after serious criticism was levelled at the inspection of Bangor Grammar, a large boys' school.
The inspection in 1993 gave the school a clean bill of health for the care and welfare of pupils. In February this year, Lindsay Brown, vice-principal responsible for child protection in the school, was convicted on nine counts of indecent assault and two counts of gross indecency against pupils.
An inquiry found that inspectors failed to check Dr Brown's assurances that child protection was working satisfactorily and in line with Northern Ireland Office guidelines. In fact, procedures did not accord with the guidelines and the province's chief inspector was forced to express his "deep regrets".
Northern Ireland will now pilot Scots practice of arriving without warning at schools where concerns are raised about pupils.