Above all, I am disappointed in the document's lack of research evidence. The head of the research and intelligence unit at the Scottish Office Education and Industry Department replied to a question during the conference of the Scottish Educational Research Association by saying that Achievement for All would be underpinned by a "literature search" being carried out by the Scottish Council for Research in Education. What happened to that search? Is it absent from HMI's document because it proved fruitless?
That would be difficult to achieve given the high calibre of researchers at the SCRE. Or did the search come up with conclusions that did not quite match the conclusion of HMI? If so, and it seems the likely explanation, it would be reprehensible and further disturbing evidence of lack of impartiality in the Inspectorate.
So what does research tell us about mixed ability and setting? If it does not accord with the "realpolitik" of which Mrs Ritchie reminds us, namely that David Blunkett, Labour's education spokesman, has sought to distance himself and the party from mixed-ability teaching, what am I as an educationist to do? It surely is my duty to bring the evidence out into the open and to challenge dogma from the right and the left, even if it leaves me open to personal attack.
The evidence on mixed ability and setting dates back to the 1960s. In 1964, Jackson surveyed 660 schools and concluded that the measures used to stream pupils were invalid, subjective and unreliable. In the same year, Daniels found that of all the pupils thought to be able to benefit from moving up a stream, only about a quarter ever did. In 1970 the Barker-Levy study showed that middle-class children predominated in A streams.
At around the same time a number of studies were carried out (Douglas, 1964; Goldberg et al, 1966; NFER, 1972) which showed that forecasts of achievement made at the point of selection are self-fulfilling, that there were gains among students taught in mixed-ability classes rather than in sets, and that there were higher participation rates in school activities when there was mixed-ability organisation.
Perhaps the key study of the late 1970 was Postlethwaite and Denton in The Banbury Experience, which found little difference in academic attainment across mixed-ability and set classes, but argued that patterns of social interaction were more varied in mixed-ability classes. A more local, small-scale study of an English department (McPhee) in the same year found little difference in attainment between mixed-ability and set groups. A year later the seminal work on school effectiveness, 15,000 Hours (Rutter et al) found that on average children in streamed and unstreamed classes made similar progress.
Since then, research has been thin on the ground as the issue in the 1980s became less of a political football. But it has to be noted that in Scotland the comprehensive school - the real target of the New Right - has been a success story, with increased attainment across the board. This is reinforced by a recent survey of comprehensive education across the UK, Thirty Years On, in which Benn and Chitty conclude that there is no evidence to support the view that pupil attainment increases in set classes.
It is Mrs Ritchie and Douglas Osler, head of the Inspectorate, who are tilting at windmills, not me. It is quite clear, as we found when we researched Towards a Climate of Achievement (McMichael and Boyd) and the National Union of Teachers' study Schools Speak for Themselves (MacBeath et al), that pupils have a valuable insight when it comes to discussing effective schools. They are only too aware of the range of talents which their peers have, but they believe that they should all be treated with equity.
While Mrs Ritchie's argument is predictable, HMI should know better. Education of Able Pupils P6 to S2 is a far more balanced document which concluded that no one form of classroom organisation will by itself meet the needs of able pupils. What is required is a policy on effective learning and teaching for all pupils.
Brian Boyd is associate director of the Quality in Education Centre, Strathclyde University.