In the most extensive poll yet conducted on the issue, The TES Scotland found that the overwhelming majority of heads are far from convinced about the merits of setting as an answer to the problems of the first two secondary years.

Returns from almost 70 heads across the country - one in six of the total - reveal a mixed picture. Four schools do not set at all in S1 or S2, eight set in S2 only and 13 set in just one subject (routinely maths).

Overall, 62 schools have setting in S1-S2; 23 say they want to do more; 20 have it under consideration; and 23 reject any increase, some on principle and others because they already set in three or more subjects or because of staffing restrictions.

The general response, however, is “let’s wait for the evidence”.

In his breakfast meeting with secondary heads recently, Mr McConnell said:

“We know that the first two years of secondary schooling moves too fast for some and too slow for others. So let’s make more use of setting.”

But Cathy Jamieson, Education Minister, has cautioned against any move that smacks of a “one size fits all” approach.

Colin Finlayson, head of James Gillespie’s High in Edinburgh, which sets in maths and English in S1 and S2 , is representative of the overall responses. “The benefits of setting are not conclusive,” Mr Finlayson said. “Sometimes it helps children and sometimes it can create low expectations and disadvantage. Setting is not a universal solution to the problem of differing abilities and schools must seek a variety of solutions.”

The main solutions cited by most of the heads were improvements in the quality of teaching and learning, enhancing the skills of the teacher and cutting class sizes.

The professional judgment of teachers is regarded as the most reliable basis for organising pupils’ learning. But Carole Ford, head of Kilmarnock Academy, which sets in maths, English and French and wants to do more, said she suspected that if decisions were left to teacher judgment, “such freedom will lead to more setting”.

One of the few unreserved supporters of the idea is Joe Smith, head of Preston Lodge High in East Lothian, where setting takes place in maths, English, French, the social subjects and science. “I consider setting to be correct and believe that it will raise standards across the school. Principal teachers are generally in favour including some who opposed the idea a year or two ago,” Mr Smith said.

But he does not favour extending setting to music and art.

The complexities of the issue are evident, however, in the fact that two schools - James Hamilton Academy in Kilmarnock and Uddingston Grammar - plan a return to mixed-ability teaching.

Bill McGregor, head of James Hamilton Academy, says his English department is making the switch after five years of combined setting and mixed-ability classes. The system failed to improve level E (5-14) passes.

Mr McGregor said the English department would ensure there were individual education plans and small group plans in place.

“Philosophically, I believe mixed ability can work with proper targeting and tracking. I am old enough to remember junior and senior secondaries and many pupils lived down to their group throughout their school careers.”

A Scottish Executive spokesperson said: “We believe that individual schools are best placed to make decisions on how classes should be organised. Ministers have repeatedly made clear that they are more interested in outcomes than processes - the bottom line will always be whether a particular approach raises the attainment level of all pupils.

“The First Minister has, indeed, called for headteachers to make maximum use of the opportunities that curriculum flexibility can bring. But his example of setting as a possible way of improving attainment is precisely that - an example, and not a universal recommendation.”

Leader, page 20 ScotlandPlus, pages 2-3