The circular was withdrawn in 1970 when the Conservatives returned to power, and effectively reinstated in 1974 on the return of Labour. But throughout the period the proportion of children attending comprehensive schools rapidly increased. In 1971 only about 40 per cent of children in UK state maintained secondary schools were in comprehensives; by 1981 this had risen to about 90per cent.

During the early 1980s there were several attempts by Conservative controlled local education authorities to reintroduce selection by academic ability. All these attempts failed. In Solihull and Richmond-upon-Thames, for example, local parents campaigned against the proposed changes and won their demands for the retention of existing comprehensive schools. The all-out frontal attack on comprehensives did not work, so a more gradual approach was adopted.

Since the mid 1980s, attempts to reintroduce selection have been more indirect. Successive legislation has introduced City Technology Colleges, grant-maintained schools, technology schools, specialist music, dance and modern language schools, and new forms of faith-based grant-maintained schools. The result has been greater fragmentation into different types of school, greater selection according to a range of different criteria and greater inequity in what schools offer. Market forces (under the guise of choice and diversity) reflect and promote a different set of values; growing inequalities between schools militate against social equity.

Last week the government made one further move against comprehensive schools with proposals that all schools be allowed to select up to 15 per cent of their pupils by academic ability.

This is thus the appropriate time to examine the principles that inspired comprehensive schools 30 years ago. What lay behind the comprehensive ideal? What has been gained or lost? How should schools be organised such that all young people are provided with an appropriate education and training irrespective of ability, aptitude, social class, gender, ethnicity or religion?

Over the next two terms the University of Oxford department of educational studies is holding a series of 14 lectures to address these issues. The lectures will survey the ideals and history of the comprehensive movement, describe the current context and the effects of recent legislation, and offer possible ways forward. There can be no simple turning back the clock, but there is a need to safeguard the ideals on which the comprehensives were built and to construct a new, appropriate education system in the light of what we have learnt from the past.

The speakers will explore the continued relevance of those original comprehensive ideals and will include Brian Simon and Peter Cornall on the ideals and history behind the comprehensive movement; David Halpin and Geoffrey Walford on recent fragmentation, privatisation and selection; Stephen Ball and Richard Pring on the social and political philosophies behind markets and competition; Denis Lawton and Sally Tomlinson on the curriculum and the future; Caroline Benn and Ted Wragg on what makes effective comprehensive education and effective teachers; Bernard Clarke on what comprehensive schools do better; John Abbott on how information technology supports the comprehensive ideal, and finally, Tim Brighouse and Stewart Ranson will talk on their ideas for a local democratic framework that embodies comprehensive values and fits them within the learning society.

All the speakers want to protect the improvements of the past 30years, but to show that comprehensive principles can be reapplied in the very different social and economic circumstances of the next millennium.

The future will demand that we take far more seriously the need to develop a range of personal and social abilities. The different forms of intelligence will need to be nurtured; the new opportunities for organising learning which technology makes possible will need to be exploited. Most of all, however, there will be a need to ensure that every child has access to the highest possible quality schooling and that provision does not depend on social background.

The demands and opportunities of the new millennium may require modification to the form of comprehensive schools that thrived in the 1970s, but the series of lectures will seek to show that the ideals on which they were based are very much worth re-examining and re-affirming.

The lectures will be held at Oxford University on Wednesday evenings, starting on January 24, and sponsored by the Centre for the Study of Comprehensive Schools, Blackwell Publishers, and the Standing Conference on Studies in Education. The TES will aim to publish some of the highlights of the series, and encourage debate on the issues raised.

Geoffrey Walford is lecturer in educational studies and Richard Pring is professor of educational studies at the University of Oxford