Fears are growing among teachers' leaders, Whitehall insiders and senior MPs that the new curriculum agency will lack the clout needed to prevent ministerial meddling in what schools teach.
The job of the Qualifications and Curriculum Development Agency, which becomes operational when new legislation is passed by Parliament, is to take on the curriculum work done by the Qualifications and Curriculum Authority, while the regulation of exams will become the responsibility of Ofqual.
But there is widespread concern that the shift in status from an authority to an agency will coincide with a downgrading of its ability to stand up to ministers should they try to tinker with the curriculum.
The imminent departure of two big hitters, Ken Boston, the QCA's chief executive, and Mick Waters, its head of curriculum, is causing particular anxiety.
Barry Sheerman, Labour chairman of the Commons schools select committee, said: "A lot will depend on who is the first permanent appointment (as Dr Boston's replacement). I think the success of the QCA has been about having a robust, single-minded chief executive. If there is a person appointed who is a bit of cypher then I would be extremely worried.
"I want to see as much robust independence as possible because the curriculum has been a political plaything for too long under Labour and the Conservatives."
Government intervention in the new secondary curriculum provoked an outcry from heads two years ago. The revamp was supposed to give teachers more flexibility over what they taught, but a string of ministerial pronouncements, demanding the inclusion of everything from Thomas Hardy to cooking and the British empire, led the ASCL heads' union to complain that the curriculum was dictated by newspaper headlines.
The secondary review was headed by the QCA, under Mr Waters. But the current primary review has been outsourced to Sir Jim Rose, with a team of civil servants and support from the QCA.
One Whitehall source who worked with the authority until recently, said he feared the decision was part of wider move by the Government to extend its influence over the curriculum, which could lead to a diminished, advisory role for the new agency.
"Since 1988 when the national curriculum was set up, there has been a consensus that ministers should interfere as little as possible, but that seems increasingly under threat," he said.
A spokeswoman for the Department for Children, Schools and Families said the QCDA will not be an authority because it would no longer be a regulator of qualifications.
The word agency better suited its responsibilities, she said. It would be a "key source of expertise supporting ministers".
She said: "We utterly refute the claim that there will be ministerial interference in the curriculum.
"The QCDA is being give the same statutory role in the curriculum as its predecessor."
But John Bangs, head of education for the NUT, said that did not mean it would be able to carve out the same position Dr Boston had achieved for the QCA. "As a new agency, it will not have the same self confidence and will have to start from scratch," he said. "Our concern is it will not have the same ability as the QCA to restrict ministers' bad ideas."