In the latest and most powerful attack so far on political meddling in the curriculum, Duncan Graham, former head of the National Curriculum Council, suggests that ministers are guilty of 'wilful distortion for political ends'.
The allegations follow accusations from other former advisers that ministers are packing education advisory committees with right-wing ideologues.
Ann Taylor, Labour's education spokeswoman, has written to John Patten, Secretary of State for Education, asking for an assurance that he will 'refrain from similarly subverting the national curriculum for political purposes'.
Mr Graham, who resigned from his job last year, says in a book to be published next month that the worst ministerial offender was Kenneth Clarke, Mr Patten's predecessor, who interfered over the history curriculum and teaching methods in primary schools.
Mr Clarke decided history should end before the present day. 'The decision of when the end date should be was the result of a Dutch auction between Clarke and his officials. His opening bid was 1945.' He eventually settled for 20 years before the present. The curriculum council was not consulted. When Mr Clarke decided to cut back the national curriculum, he did so without asking the council's advice.
Mr Graham says that the curriculum council and the School Examinations and Assessment Council, set up by statute to offer the Government independent advice, eventually 'had no more status, than any other pressure groups, perhaps less'.
His words echo those of Peter Dines, former secretary of the examinations council, who said recently that the body was now so much under ministers' sway that it was close to breaking the law.
Professor Eric Bolton of London University's Institute of Education, who retired last year as senior chief inspector of schools, said: 'You could say the whole idea of a national curriculum is political interference. It is ministers' influence over testing which borders on the undesirable. If they say only three things will be tested in primary schools then you can be sure only three things will be taught in primary schools.'
Mr Graham says civil servants also meddled. He recalls protesting to Kenneth Baker, then Secretary of State for Education, about a letter he had signed curtailing some of the curriculum council's activities. Mr Baker 'looked at the letter and could not believe he had signed it. It was one of those magic moments'.
A Lesson for All - the Making of the National Curriculum, by Duncan Graham and David Tytler, will be published by Routledge; pounds 12.99.