For those who are keenly interested in the educational policy direction of the next Labour Government, signals are all. There were strong new signals in his speech; some clear and one, I am afraid, which will lead to confusion.

For the first time, Tony Blair unequivocally supported the principle of comprehensive education. That must be welcome. The existence of grammar schools will create a two-tier system. Selection would indeed be a mistake of monumental proportions. The contrast with the Secretary of State’s March speech, heralding the June White Paper on schools and local education authorities, could not be more stark.

Having made a clear commitment, Mr Blair then moves into a possible minefield. What is now evident is that both Government and Opposition have shifted their attention away from the structure of the national curriculum and assessment. Great interest is now being shown in pedagogy - the nature of teaching itself and the best ways of stimulating learning.

Previously, educational outcomes were the sole concern of Government. How teachers arrived at those outcomes was up to them. The National Curriculum Council’s publication Curriculum Guidance No 3: The Whole Curriculum, made it explicit that: “It is the birthright of the teaching profession and must always remain so, to decide on the best and most appropriate means of imparting education to pupils.”

In the minds of Government and Opposition, that is no longer the case. The great temptation is to prescribe methods of teaching.

Yet pedagogy is so much more than a science. The relationship between teachers and pupils constitutes the most complex of chemistries involving empathy, politics with a small ‘p’, experience, humility, knowledge and enthusiasm. Fundamentally, those relations are pragmatic. As Tony Blair himself said, a year ago, in his speech “Reaching our True Potential”: “The end is high achievement, I am a pragmatist when it comes to how we achieve that high achievement.” Yet, in his most recent speech, he stated that: “In government, we will start from a general presumption in favour of grouping according to ability or attainment unless a school can demonstrate that it can meet the heavy demands of a mixed-ability approach.”

Here, we edge into dangerous territory. Most schools respond pragmatically to the educational needs of their pupils. Setting and grouping is not seen as an ideological response and it takes place in many schools. However, in an effort to reassure those with a nostalgia for selection, the idea being put forward is that grouping is its rigorous alternative.

Unfortunately, he is in grave danger of facing both ways. A recent summary paper from the Institute of Education concluded that: “Stress on ability grouping minimises the importance of student, teacher and parental effect. The concept of differential ability sets a ceiling of what can be expected from a child.”

David Reynolds believes that those interested in improving schools should draw lessons from the fact that in Taiwan, “mixed-ability classes...only move on from a topic when all children have grasped it” (TES, June 7). Whatever individual reactions may be to David Reynolds’ work, it has been enormously influential both on the Chief Inspector of Schools and the Labour front bench.

The trouble with trying to make policy by sound-bite is that you can end up promoting contradictory policies. What is the Labour party’s response to the evidence from the Institute of Education and David Reynolds? Is setting and grouping a model all schools should adopt?

I prefer the pragmatic conclusions of the ‘Three Wise Men’ report: “The critical notion is that of fitness for purpose. The teacher must be clear about the goals of learning before deciding on methods of organisation. Whole-class teaching, group work and one-to-one teaching are each particularly suited to certain conditions and objectives.”

I would urge Tony Blair to stand back and reflect again.

Doug McAvoy is general secretary of the National Union of Teachers.