Subject experts fear the increasing amount of time pupils are spending on literacy and numeracy is squeezing the breadth out of the national curriculum.
Their worries have been exacerbated by some of the changes to teaching due to be introduced over the next two years.
But the debate over how broad the curriculum should be began before it was introduced 20 years ago, when Margaret Thatcher and Kenneth Baker, her education secretary, clashed over it.
Lord Baker's autobiography recounts how he wanted all pupils to study technology, languages and history to 16. On the other hand, his prime minister wanted to stipulate compulsory study of only English, maths and science.
Lord Baker's subsequent national curriculum consisted of the breadth he wanted, in the shape of 10 compulsory subjects.
He writes: "I believed that if we were to concentrate just upon the core subjects of English, maths and science, then schools would teach only to them and give much less prominence to the broader range which I felt was necessary."
In an interview with The TES on the 20th anniversary of the national curriculum, Lord Baker said he still stood by those principles.
"There should be a broad, general curriculum, not just of English, maths and science," he said. "Children need encouragement in culture, art, music and games."
Lord Baker said he regretted that he had not pushed to add an hour to the school day in the late 1980s to give more time for the full curriculum to be taught.
When it was put to him that there was much evidence that test-driven teaching was narrowing the curriculum, he said he backed his decision to introduce a testing system alongside the curriculum.
He was also disappointed by a decision by Gillian Shephard, a Conservative successor, to make history voluntary in key stage 4.
"One of the worst things was when history was dropped at 14," Lord Baker said. "We are the only country in Europe, apart from Albania, where this is possible."
He said he was unconvinced there was any move afoot to step away significantly from his original "broad and balanced" ideal.
However, teachers have reported that non-core subjects have sometimes been sidelined as schools focused on lessons that improved their standing in the league tables.
Manchester University's Centre for Formative Assessment Studies has shown, for example, how the amount of time devoted to English and maths in primary schools increased from 42 to 49 per cent from 1996 to 2006.
This was a result of schools introducing the national literacy and numeracy strategies and seeking to improve their league table results in these subjects, cutting time for other subjects, such as music.
The introduction of English and maths as the central subjects in GCSE league tables in 2006 also seems likely further to emphasise these disciplines in secondaries.
The TES reported last year how a National Strategies scheme, introduced as the new league table measure came in, selected C-D borderline GCSE pupils to be given extra tuition in English and maths.
Subject experts are concerned that coming changes to the secondary and primary teaching could further narrow the curriculum.
For example, the current Rose review of the primary curriculum, due to lead to changes in 2010, has been billed as freeing more time for schools to focus on the basics of English and maths.
Similarly, changes to the secondary curriculum to be introduced this year are in part designed to make more time available for catch-up classes in English and maths.
In its evidence to the Commons select committee's curriculum inquiry, the Government said the secondary reforms were particularly designed to address employers' need for school-leavers with "functional skills".
But a DCSF spokesman said that this did not equate to a narrowing of the curriculum. "We make no apology for the focus on the core subjects of English, maths and science because they are the key to children's future success in the classroom and beyond," he said.
"Catch-up lessons help those pupils who need it to master the basics, which is a vital for studying other areas of the curriculum."
Earlier this month, Jim Knight, the schools minister, described English, maths and science as "priority subjects" when quizzed by MPs as part of the select committee's curriculum inquiry.
Practical skills focus narrows courses
It is not just the growing focus by schools on English and maths which may contribute to a narrowing of the curriculum - it is also how the focus has changed within those subjects.
Increasing emphasis is being given to aspects that are deemed to be of practical use to pupils later in life, such as spelling, punctuation and facility with figures. Next year a new English GCSE will be introduced that focuses on generic skills.
The time on the course which pupils will spend studying literature will drop from 35 to 20 per cent. Higher achievers will take new, separate GCSEs in English literature and English language. Then in 2010, "functional skills" tests will be introduced, which are designed to assess pupils' understanding of core concepts of English, maths and ICT.
Bethan Marshall, senior lecturer in English education at King's College, London, said: "The emphasis is very much now on the functional aspects of the subject. But there is not a direct link between being able to spell and punctuate, for example, and being able to write well."
Tony Gardiner, a past president of the Mathematical Association, said that countries such as Japan, China and Korea were forging ahead in primary maths education by focusing on deep conceptual understanding of the subject, rather than simply ensuring that pupils had mastered aspects of the subject which had immediate real-world spin-offs.
Simon Gibbons, chairman of the secondary committee at the National Association for the Teaching of English, said if there was a drive towards functional aspects of the subjects, the curriculum was not to blame. He said: "What matters is how the curriculum is assessed. The new secondary curriculum, for example, emphasises creativity. But this is not assessed, so it will not be given so much attention. The curriculum is the servant of assessment."