The origins of the national curriculum lie in the 1970s, the decade when Britain appeared close to bankruptcy. Unable to arrest what they saw as headlong national decline, politicians made schools the scapegoat. The teacher’s classroom was then a professional castle, and even heads hesitated to prescribe what happened within its walls. With the 11-plus largely abolished, the syllabuses for exams at 16 were the only constraints on teachers’ freedom.

The Labour Prime Minister James Callaghan, speaking at Ruskin College, Oxford, in 1976, said all this should change. There was too much variation in what children learned, too little regard for the basics of English and maths, and insufficient attention to the needs of industry. Callaghan’s proposal for some kind of national core curriculum had strong support from civil servants at the education department, and more cautious support from Her Majesty’s Inspectors. The teaching profession vehemently opposed it.

After the Conservatives returned under Margaret Thatcher in 1979, local education authorities were told to produce curriculum policies, but the PM thought the results were too woolly. She wanted a national core curriculum of English, maths and science with simple pencil-and-paper tests.

Teachers feared the core would become the whole, and schools would return to the narrow, mechanistic curriculum of the 1930s. Kenneth Baker, the Secretary of State from 1986, agreed. He argued that, although English, maths and science should indeed be called the “core subjects”, another seven “foundation subjects” - history, geography, a modern foreign language, art, music, PE and technology - should also be compulsory; otherwise, they would not be taken seriously. He appointed working groups of specialists to draw up study programmes, plus attainment targets, for each subject. Teachers, determined to avoid Thatcher’s curriculum, reluctantly co-operated with Baker’s plans.

The monster that followed - the most detailed and prescriptive national curriculum in the world - was inevitable. First, the wider the national curriculum became, the greater the fear that anything left out would not be taught at all. Second, the various working parties had a vested interest in maximising the time devoted to its subject and thus enhance its status.

Third, the national curriculum had to satisfy both the Tory traditionalists who wanted knowledge and old-fashioned exercises - grammar in English, long division in maths, dates in history, “capes and bays” in geography - and the majority of teachers, who wanted skills, practical applications and creative imagination.

As the working parties reported, the problems grew. Science annexed half the geography syllabus. Thus denuded, geography drifted into political and social studies, which ministers didn’t want at all. Home economics (or domestic science) had to be accommodated in technology. Dance had to be shoehorned into PE.

Everybody from the Secretary of State downwards had their pet topic for inclusion: Baker wanted primary children to learn poetry by heart, while one of his successors, Kenneth Clarke, wanted jazz in the music curriculum.

Nobody except heads had any interest in ensuring that things remained manageable within school timetables and resources. The National Curriculum Council valiantly struggled to keep down the number of attainment targets and statements. Maths started with 354 targets which were reduced to 14.

Geography started with 269 statements which the council wanted reduced to 170. The compromise was 211. Sometimes, the horse-trading descended into farce. Historians wanted to teach everything up to 1990; Clarke insisted that anything after 1945 was current affairs. It was eventually agreed that history should stop 20 years before the present day, whenever the present day happened to be.

The ink was hardly dry before, with teachers boycotting the first tests, ministers asked Sir Ron Dearing - a former civil servant who became a ubiquitous government troubleshooter in the 1990s - to review it. On his recommendation, study programmes were simplified and schools told that, in theory, they could use 20 per cent of the timetable at their own discretion.

Three developments brought the curriculum closer to what Thatcher had wanted. First, the publication of school league tables for test results in English, maths and science made these three subjects of overriding importance. Second, Labour’s introduction of literacy and numeracy hours to primary schools, in 1998 and 1999, alongside its relaxation of requirements in the foundation subjects, gave renewed emphasis to the basics. Third, by lifting the requirement that all 14 to 16-year-olds must study a foreign language, Labour reduced the compulsory national curriculum for that age group to the core subjects, a process that had begun under the Tories.

While giving more freedoms with one hand, ministers imposed more demands with the other. Labour insisted all secondary pupils should learn citizenship and all should have some work-related experience. Assessments for five-year-olds were introduced, creating a benchmark for judging results for seven-year-olds; the national curriculum was thus informally extended into the pre-school years. With the introduction of the early years foundation stage for 0-5s in 2008, the extension will be formalised.

The literacy and numeracy hours took government for the first time explicitly into teaching methods, a development confirmed this year when Ruth Kelly, the former Secretary of State, announced she would require synthetic phonics to be the prime strategy for teaching beginners to read.

We have come a long way in 30 years. The ramparts of the professional castle have been well and truly stormed.

TAMING OF THE SECRET GARDEN

1976 Labour Prime Minister James Callaghan’s Ruskin speech heralds the end of the curriculum as a secret garden.

1979 Margaret Thatcher becomes Prime Minister in a Tory victory. Kenneth Baker, one of her education secretaries, claimed she got her views on education from her hairdresser and her cleaner, and wanted only English, maths and science to be compulsory.

1988 Education Reform Act heralds a 10-subject national curriculum.

1989 National Curriculum introduced in primaries.

1991 First national SATs at key stage 1 are hugely time-consuming and need revision.

1992 First secondary performance tables published.

1994 Sir Ron Dearing chairs group to slim down curriculum.

1998 National Literacy Strategy introduced by new Labour; numeracy strategy follows a year later.

2001 Foundation stage begins.

2002 First primary school targets for English and maths are not met.