I suppose that anyone asked what was the main novelty introduced by the 1981 Education Act would reply that it was the concept of inclusion.

That Act was based in part on the committee I chaired, and the report we published, and the concept of inclusion was our recommendation. Yet from the start, it was a matter of deep division within the committee, and within the report there were cautionary words about the extent to which inclusion should be taken as an ideal.

There were committee members who were enthusiasts, even fanatics. Ted Britton, then the recently retired general secretary of the NUT teaching union was chief among these. He held that the ideal of comprehensive education would not be fully realised until all children, whatever their abilities, were taught together in the same classrooms.

Margaret Thatcher, as the secretary of state for education and science, had given the committee the remit to examine the education of “handicapped children and young people”.

At our very first meeting, we changed our terms of reference to “the education of children with special educational needs”, a phrase that was introduced in the original briefing paper for the committee written by civil servants at the Department of Education. It was, and I believe still is, a useful phrase, in that it switched attention away from what was wrong with a pupil to what had to be done to help her or him to make educational progress. It also chimed with what was the crucial significance of “inclusion”, namely that in most classrooms there were already many children who needed special help if they were to benefit from their education. We were not only advocating the introduction of new categories of children into mainstream classrooms, but widening the scope of the concept of “the handicapped” to include many already struggling in the mainstream.

I formed an image of education as a road on which children embarked when they first went to school and down which they all walked towards the goals of competence, independence and imaginative pleasure. For some the road was easy, smooth and mainly enjoyable; for others it was beset by obstacles, over which their teachers had to help them.

But there was nothing in this image that required all children to be taught in the same classroom. It required only that their needs be met. And it was obvious to most of the committee, by the end of our deliberations, that for some children, and especially autistic children, being part of a class of rowdies - not only noisy, but liable to knock into you - was nothing but torture and a bar to learning. Another risk in an inclusive class was that the children with special needs would be taught mainly by teaching assistants, not qualified teachers, still less by those qualified in teaching children with SEN. We should have made more of this risk.

I was, therefore, delighted when, in a ministerial statement in March 2011, Michael Gove promised to “remove the bias towards ‘inclusion’” and provide a wider choice of different kinds of school (including, as I hoped, some small schools, in which some children can best flourish).

The bias towards inclusion was not the only thing wrong with the 1978 report, but, because it seemed revolutionary at the time, and because it was, at least at first, popular with many parents, because it promised to remove the stigma attached to attendance at a special school, it may have been one of the most damaging in its consequences.

Baroness Warnock led the seminal 1978 report on special educational needs.

UCL Institute of Education is holding a public debate, sponsored by Tes, to mark the 40th anniversary of the Warnock Report on Tuesday 8 May 2018.

The evening event, called “What if… we thought anew about how we support special educational needs and disability in our schools?”, will feature a discussion by panellists, including writer and actress Sally Phillips, special school principal Vijita Patel, disability rights activist Tara Flood and emeritus professor of SEN Klaus Wedell. There will also be a video contribution from Baroness Warnock. For details, click here.