That is not to say the opposite, however: that the report is worthless because the definition of effectiveness is restricted to certain kinds of learning; or that, because the data used came from real teachers and real children in real schools, the conclusions lack forensic precision; or even that it only confirms what everybody knew.

The pupil achievements that teacher effectiveness was measured against may be limited. But they are vital to our individual and collective futures. Teacher effectiveness has to be tested in real life rather than under laboratory conditions. And there would be something very wrong indeed if this outsider’s view of successful practice threw up too many surprises for the profession.

It remains to be seen how many of the teacher characteristics HayMcBerassociates with pupil success are among the real causes of that success. Some may just be incidental to it or even the consequence of it. It is no revelation, for instance, that classroom disruption reduces effectiveness. But what comes first, the chicken of good behaviour or the egg of satisfying learning? And how far can an individual teacher alone raise pupil aspirations or produce good order without the wider support of home and school?

This report provides a taxonomy of the different factors thought to contribute to effectiveness rather than a model of how they work or a proven recipe for combining them. The usefulness of this analysis will be measured by how far it provides a conceptual map that demystifies effective teaching and contributes to a common language for talking about what really improves learning.

The Government’s coyness about what it cost is more about political than commercial sensitivity. The profession should rejoice that so much has been invested in the search for a more systematic basis for teachers’ professional development - but subject HayMcBer’s ideas and “broad judgments about teacher effectiveness” to its own tests of usefulness and reliability.