Academy chains feted by the Government for "driving up standards" are failing on its own new measure of academic "rigour", The TES can reveal.
When education secretary Michael Gove introduced the English Baccalaureate (EBac) last year, he said he expected it to show how previous league tables had encouraged some schools to "offer certain non-academic subjects rather than more rigorous academic subjects".
Now Government figures show that the three academy chains Mr Gove says he most admires are among the worst offenders.
Nationally, 15.6 per cent of pupils achieved an EBac, which requires GCSEs or IGCSEs of at least grade C in English, two sciences, maths, history or geography, and a language.
But a TES analysis reveals that of the 16 academies 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. In three, no pupils at all met Mr Gove's benchmark.
Figures show that other major academy chains also fared badly on the EBac. Large discrepancies between EBac scores and other, looser GCSE benchmarks suggest widespread use of "equivalent" qualifications, dubbed "pseudo- vocational" by critics.
Ministers have justified their huge academy expansion with claims that their GCSE results are improving faster than average and that chains are particular drivers of success. But figures show academies are more prone to EBac failure than other secondaries with disadvantaged intakes.
Anastasia de Waal, education director of think-tank Civitas, which has been campaigning for greater transparency on academies, said: "Michael Gove is championing academy chains with a different recipe of success to his emphasis on core academic knowledge for everyone, regardless of background."
Asked last year whose ideas he most admired in education, Mr Gove highlighted "those at the Harris academies, and those at chains such as Ark and the Haberdashers', who are driving up standards in the poorest areas".
He has also singled out the Harris Federation for an "approach towards education which rests on traditional subject disciplines, rigour, and an expectation that every child, whatever their background, can follow a basic academic curriculum".
But in six of the eight Harris academies where GCSEs were taken last year, no more than 6 per cent of pupils achieved an EBac.
Last year Mr Gove wrote to Bromley Council urging it to back Harris in a takeover of Kelsey Park Sports College, south London, because the academy chain had "a track record second to none".
In fact, Kelsey Park achieved a better EBac score than five of Harris's eight academies. The federation did not respond when asked to comment.
None of the five Ark academies where GCSEs were sat saw more than 5 per cent of its pupils achieve an EBac, with two scoring zero.
Ark, a hedge-fund-backed children's charity, has been in control of two of the academies since 2006 and 2007. But Ark spokeswoman Lesley Smith said some of the teachers they inherited were used to teaching Btec qualifications and that training for GCSEs took time. She also cited low primary school attainment, the subject combinations pupils chose and the use of non-GCSE "equivalent" qualifications as factors in the low EBac results.
Ark wanted all pupils to achieve EBac standards, she said, but it would take longer than five years.
In the three Haberdashers' academies where GCSEs were sat last year, 2, 6 and 32 per cent of pupils achieved an EBac. A spokesman for Haberdashers', a City livery company, said the schools had "constantly improved" on previous benchmarks and would respond to the EBac.
Elizabeth Sidwell, chief executive of the Haberdashers' Aske's Federation - which runs two of the three Haberdashers' academies, including the highest performer - was recently appointed England's next schools commissioner by Mr Gove.
"The federation's first priority is to actively pursue English and maths with three other good GCSEs for all," Dr Sidwell said. "EBac subjects have always been and will continue to be on offer for those students who wish to follow that route."
The TES analysis uncovered low EBac scores in three other major academy chains (see box, right).
A spokesman for charity E-ACT cited "significant improvement" on other GCSE measures and said it was looking at including history, geography and languages "where this is appropriate".
An Oasis spokesman said its academies had made a "great improvement" on other GCSE measures. The "next stage" was to "continue to offer subjects that may be included in the English Baccalaureate".
United Learning Trust (ULT) did not respond when asked comment on scores in its academies.
A Department for Education spokeswoman said: "We want to see more young people in all schools, including academies, doing modern languages alongside GCSEs in English, maths, science and humanities. We recognise that this may take longer in the academies that replaced underperforming schools and initially concentrate on the basics."