A key Government policy for school improvement since 2002 has been the creation of publicly funded schools, free of local authorities. Academies are claimed to achieve better GCSE results than local authority schools. The key question - do they produce better results? - is unavoidable.

The evidence on this is clearly mixed, with statistics on academy results questioned by the introduction of education secretary Michael Gove’s English Baccalaureate.

There are real doubts about whether the EBac is the right mix of subjects in our schools. But, given that this is the Government’s chosen measure, it throws a glaring light on academy performance.

The press focused on the Government statistic that only 16 per cent of pupils achieved the EBac. But the statistics were even worse in academies. The TES reported that in 58 of the 187 academies where pupils sat GCSEs last year, no EBacs were achieved (“Academies outperformed on EBac by other `challenging’ secondaries”, 28 January). On the other hand, only 8 per cent of non-academy comprehensives and secondary moderns failed to score on the EBac.

Academy schools can argue that the previous Labour government set up academies in deprived areas. So a comparison has to be made with schools with similar intakes. However, a study of schools with similar proportions of pupils on free school meals, a total of 970, showed that only 169 completely failed on the EBac, a figure of 17 per cent. This is significantly better than the 31 per cent of the comparable academy proportion.

An analysis of the most admired chains of academies favoured by the Government showed they had achieved a pass rate of only 6 per cent compared to the 16 per cent achieved nationally (“Gove’s favoured academies are failing to meet his own standards”, 25 February). Of the 16 schools controlled by Harris, Ark and Haberdashers’ Aske’s where GCSEs were sat last year, only three saw more than 6 per cent of its pupils achieve the EBac.

The debate on academies is approaching a critical point. The Government cannot claim academies are successful when their measure of success shows they are not.

Professor Richard Pring, Green Templeton College, Oxford; Trevor Fisher, editor, Education Politics; Sir Peter Newsam, former chief schools adjudicator; Chris Price, formerly principal parliamentary secretary; Professor John Elliott, Centre for Applied Research, University of East Anglia; Professor Michael Fielding, Institute of Education; David Wilcox, chair, Local Government Information Unit; Professor Bob Moon, Research Group on International Development in Teacher Education, Open University.