Leading independent schools have "grave reservations" about key elements of the controversial GCSE replacement qualifications planned by ministers, TES can reveal.
The Headmasters' and Headmistresses' Conference (HMC) group of elite schools is opposed to English Baccalaureate Certificates (EBCs) being run by a single exam board in each subject and to assessment being 100 per cent external exams.
The organisation, representing more than 250 fee-paying schools, will reveal its concerns to government through an official consultation that closes on Monday.
"There are some broad areas of aspiration that we entirely share (with government) but when it comes to specific proposals these are areas where we have grave reservations," William Richardson, HMC general secretary, told TES.
It was also revealed this week that Glenys Stacey, Ofqual's chief regulator, wrote to the education secretary Michael Gove last month to warn that the aims of EBCs may not be "realistically achievable" through the single assessment he had envisaged.
She warned that EBCs may not initially be suitable as school accountability measures and suggested sample testing as an alternative. In the long term their use as accountability measures could limit the "classroom experience" and they would be less reliable than GCSEs, she said. Ms Stacey also repeated her concerns about the single exam board model.
Other critics include leading academic assessment experts, teaching unions, exam boards and Graham Stuart, the Conservative chair of the Commons Education Select Committee.
An opinion poll in October suggested that three-quarters of teachers and nearly two-thirds of the public were opposed to the plan to abolish internal assessment such as coursework. Dr Richardson said that HMC members agreed. "We don't like this low-trust kind of approach," he said.
The Association of School and College Leaders (ASCL) is also critical of the EBC plan in its consultation response and argues that it could be "extremely divisive", prompting independent schools to reject the EBC and adopt "an entirely different qualification structure from that of the maintained sector".
Dr Richardson said it was too early to predict whether this would happen, but warned that HMC schools were also against the way ministers wanted EBCs to be run. "We are opposed to the proposed franchising of individual subjects to single (exam) boards," he said. "Our members like diversity and choice among boards and we also fear that boards who solely offer a subject will be less accountable on marking and appeals."
He stressed that a GCSE overhaul was "overdue, necessary and a good idea". He added that HMC schools agreed on the need for "more rigour", "more sophisticated examinations" with broader specifications and "much clearer differentiation" between grades.
The ASCL said that its soundings suggested that 96 per cent of secondaries did not think EBCs would enable them to raise the achievement of all their pupils. It argues that there should have been a "full-scale review" of all qualifications for 16-year-olds.
"Instead we have been presented with a proposal and asked only to comment on the detail," its response said. "This reform will only be successful if those who have to implement it feel involved."
The NUT and heads' union the NAHT have also joined forces to demand more consultation on the plans.
A Department for Education spokeswoman said: "The EBCs will be rigorous and high quality. They will drive improvements in all qualifications by acting as a benchmark.
"Moving towards a single exam will help students gain a broad understanding across the subject - and end competition between exam boards, which has contributed to the race to the bottom."
A 'clean break'
Education secretary Michael Gove made a robust defence of his reforms to key stage 4 qualifications this week when questioned by MPs on the Commons Education Select Committee.
Mr Gove said he planned to scrap GCSEs rather than reform them because he wanted a "clean break" and to move to a new system. The new qualifications would be a "signal of a higher degree of ambition for the education system", he said.
When asked if he expected a lower or higher number of children to gain the same kind of achievements as they did in the current system, Mr Gove said he hoped "people would dedicate themselves to getting their personal best".
He added: "We want higher standards, we want the system to tell the truth about students. I won't shy away from the fact that with a higher bar it will be inevitable that people are going to have to work harder to clear it."