For all this feverish ideological debate, there is only one way to improve schools

The British education debate has always focused on the structure of our schools. State or private? Comprehensive or grammar? Specialist or generalist? But while we bickered for over a century about the form our school system would take, a far bigger question was routinely ignored: investment. Whichever way British politicians decided to divide our kids up into different buildings, the more important question was always about how much we spent on them and their teachers. Top-price teachers in top-whack buildings can make progress with classes however they are sliced up; underpaid, low-quality teachers in lousy buildings were always likely to fail.

The British education debate has always focused on the structure of our schools. State or private? Comprehensive or grammar? Specialist or generalist? But while we bickered for over a century about the form our school system would take, a far bigger question was routinely ignored: investment. Whichever way British politicians decided to divide our kids up into different buildings, the more important question was always about how much we spent on them and their teachers. Top-price teachers in top-whack buildings can make progress with classes however they are sliced up; underpaid, low-quality teachers in lousy buildings were always likely to fail.

This was forgotten in the boiling ideological debates of the Sixties, Seventies and Eighties. The argument about the structure of schooling was so intense and emotive that the slow deprofessionalisation of teaching - the snip-snip reduction of teachers' wages, pulling them inexorably behind comparable professions - has been allowed to pass with little comment. While teachers' wages (and, as a result, the calibre of teachers) plummeted, British politics was looking another way, fighting a different battle.

It's not hard to see why arguing about structure has always been so much sexier than quibbling about cash. The comprehensive vs grammar school debate contains fundamental ideological questions. Is there a moral obligation to share privilege around, or should an elite be granted the freedom to opt out of shared social spaces? Partisans of both sides - from Tony Benn to Keith Joseph - have delivered almost Biblical speeches about these issues.

Investment, by contrast, is dull and technocratic. Even at their best, neither Tony Blair nor Gordon Brown has given a memorable speech about the need to spend more cash on schools. It's not their fault: it isn't a topic into which you can drop quotes from Shakespeare, Dante or Sartre. Arguments about investment have always been drowned out by (to borrow a phrase from Billy Bragg) the sound of ideologies clashing.

The government resolved the debate about structure by freezing it. They accepted the status quo they inherited in 1997: a mish-mash where we have some areas with grammars (and de facto secondary moderns in the surrounding areas), a few places with genuinely comprehensive schools with a real social mix (particularly in Scotland and Wales), and many places in between.

The government could mount a grand assault on this porridge and try to harmonise the school system on one particular model. That's what the Tories want to do: they want the nation to conform fully to a grammar/ secondary model. Some Labour figures, like Roy Hattersley, would like to see the opposite: the comprehensivisation of Britain. He advocates this for good reasons: there is considerable evidence that in a school with a mix of rich and poor kids, the weakest are lifted by the most privileged.

Yet the idea of local comprehensive schools attended by everybody in the community has simply been rigged out of existence by the middle class. Comprehensives based on equal access have been replaced in most parts of the country with selection by house price. There is no social mix in "comprehensives" as they exist today, negating the whole point of them. Why bother standardising all our schools on this model?

The only way to create genuinely comprehensive schools would be to introduce busing, and to forbid anybody from opting out. This is politically impossible. It seems that the comprehensive school is simply not compatible with an age where parents make decisions based on consumer rather than civic values.

Given that there is no obvious solution to the rows about structure, the government has for seven years acted on a sensible, pragmatic basis. Rather than choosing between academic selection and selection by house price, they resolved to leave our messy schools structure broadly in place, while ramping up investment in all kinds of schools.

Yet as the government unveils its five-year plan for education today, it looks as though the classic British mis-debate is about to dominate our politics once again. The Tories have pledged "a grammar school in every town" and the widespread, full-on re-introduction of academic selection. The government is countering with some sensible, limited changes to school structure. For example, successful state schools that are over-subscribed will be encouraged to expand.

This reborn debate will be loud and shrill. It will run right up to the day of the next general election. But the truth is, as ever, that reform can only ever be the younger, punier brother of higher spending. Talk of reforming structure is pointless unless it rests on a thick bed of bank-notes.

For the past few years we have - at last - had a government that put the investment debate above the structure debate. For all its disappointments, on the core policy of investing in the public services, the second term Labour government has a record to make every previous Labour Prime Minister blush. The figures are stark: £1000 more is being spent per pupil per year than in 1997. Education takes a higher proportion of our GDP than at any time since my parents were at school.

The Tories claim that all this extra cash has somehow disappeared into a black hole so massive that even Stephen Hawking could not comprehend it. But the everyday experience of people using the public services does not match the Tory jeers. All the available polling shows that parents are seeing real improvements in their neighbourhood schools; cynicism only kicks in when they are asked about "the nation's schools" in the abstract.

So now we know: investment works, whatever the structure. The highest spending has been focused on primary schools - and that is where the biggest improvements have been felt.

The Blair Government should have the confidence to hold their line. Don't match Tory proposals about drastically reforming structure with proposals that you talk up as similarly radical; it's all a distraction, and there is no obvious alternative model to promote. Don't let the debate once more career off into that dark, dank dead end. Make this argument about Labour investment versus Tory disinvestment. Explain that whatever politicians do with school structures, British pupils will only get what we pay for.

If Britain wants the "world-class education system" all political parties talk about, then spending increases need to continue at the current rate for decades, through Labour and Tory governments alike. That will only happen if the present government hammers the case for far higher education spending into our minds now - and if they are honest about the fact that it takes higher taxes to pay for it.

Excessive talk of "radical reform" blurs the message, and makes it sound like even government ministers believe higher investment isn't working. How long will it take us to learn the lesson of the last five decades of reforming Britain's schools - that there are no magical structural changes that will compensate for cool, hard cash?

j.hari@independent.co.uk