England's Qualifications and Curriculum Authority is to be abolished in its current form, it was announced this week, with ministers taking a more direct hold over the curriculum.
The authority is to be replaced by an as-yet unnamed agency, taking on many of the curriculum and national test and exams development functions of the QCA.
Meanwhile, an independent body, likely to be known as Ofqual, will be set up to carry out the QCA's other functions: to regulate qualifications and to check on test and exam standards.
For the first time, this will allow schools to call on an independent appeals panel if they are unhappy with the marking of national tests.
Heads' leaders warned that the changes could leave schools facing more direct intervention in the curriculum by the Government, just as a period of relative freedom was in prospect.
In recent years, the QCA has been trying to position itself as a more- teacher friendly organisation, supporting what goes on in classrooms rather than telling professionals what to do.
Central to this was the review of the secondary curriculum, which concluded this year and is giving more flexibility to schools to design their own curricula.
It was led by Mick Waters, the QCA's director of curriculum, who won rave reviews from many teachers at conferences promoting the reform.
It appears the Government now wants a different approach, taking a closer hold over developments.
The Department for Children, Schools and Families argued that the new agency would have a very similar role to the QCA's since its foundation 10 years ago.
Its key role, as laid down in legislation, has been to keep the curriculum and assessment under review and to advise government.
The plans were unveiled this week as the DCSF launched detailed consultation on proposals first revealed in September. It was announced then that a new regulator was being set up, answerable to Parliament, and with the central task of reporting independently on the maintenance of exam standards.
This week's consultation paper said of the QCA's other functions: "QCA will . evolve into a development agency for curriculum, assessment and qualifications."
John Dunford, general secretary of the Association of School and College Leaders, said: "This is extremely short-sighted. The Government has a poor record of decision-making in regards to curriculum and assessment, too often allowing politics and media pressure to take precedence over sound educational priorities."
Last week, it appeared to snub the QCA by giving Sir Jim Rose, a former head of inspections at Ofsted, the task of reviewing the primary curriculum.
Sir Jim, who happens to be a QCA board member, has been given a brief to strip back the primary curriculum, making more time for English, maths and languages teaching. Ministers said last week this would be less prescriptive, with schools able to tailor provision to pupils' needs.
But Barry Sheerman, chairman of the Commons Children, Schools and Families Select Committee, this week told Ken Boston, QCA chief executive: "You are the experts on the curriculum. The Government has announced yet another inquiry into the curriculum, not by the QCA, but by Jim Rose. I would be sulking if I were you."
Mr Sheerman also questioned whether Sir Jim had been appointed because he was more of a political "fixer" than Dr Boston, who has a record for challenging, albeit occasionally and often cautiously, the ministerial line.
Dr Boston said the QCA would operate as Sir Jim's chief source of advice for the review, and co-ordinating a consultation with teachers.
The new regulator, formally called the Office of the Qualifications and Examinations Regulator, will be established from April, before being set up officially, following legislation, in 2009.