But many questions remain about when and what extra cash will appear

A prime minister, unnerved by the reams of relentlessly negative headlines which only the NHS in the depths of a winter crisis can inspire, makes an unexpected promise in the middle of a television interview which changes the course of health service history. It happened in January 1988; then it was Margaret Thatcher on Panorama announcing a root and branch review of NHS funding, which led eventually to the internal market. And it has happened in January 2000, with Tony Blair on Breakfast with Frost declaring he wanted to raise UK health spending to match the European average.

Like Mrs Thatchers statement, Mr Blairs as stunned the service and caught his opponents wrong-footed. But it raises more questions than it answers. Campaigners for better NHS funding have for years leant for support on the statistic that the UK spends a smaller percentage of its gross domestic product on health than its European neighbours. Therefore, the NHSs budget must be inadequate, the received wisdom says, without much scrutiny ever being devoted to the argument. That scrutiny will happen now .

So is this latest government health target worthwhile? The Conservatives used to waft away the GDP argument by claiming it proved nothing: the NHS was far more efficient than other European health services, so chasing this holy grail would simply waste money. But few NHS managers would quibble that the service is underfunded, and increases on the scale proposed would make a real and appreciable difference - they will have to, or the game really will finally be up for a tax-funded health service.

Yet is what Mr Blair told Sir David Frost all it seems? No-one feels very sure whether it amounts to a firm commitment or an aspiration. It may have removed the government smartly from the painful hook of the winter crisis, but will it be as appealing a propaganda weapon up to and beyond the next election? It will involve vast expenditure - which will undoubtedly affect other public spending programmes - to achieve not pre-eminence in the EU health spending league but merely the average.

And exactly how is that money to be spent? How much freedom will managers have to direct it to where they know the greatest needs lie?

Is it to be funded by a tax increase or solely from the chancellors budget surpluses? One seems politically unlikely, the other economically uncertain: government finances are buoyant now, but the economy will inevitably take a downturn, and the traditional point is soon after an election, which will be long before 2006, when Mr Blairs EU average will be reached, according to current calculations.

Those calculations raise questions themselves, for averages change. As UK spending increases, that in itself will push up the EU average, so the government may have to find more than it bargained for, as it will if the economy grows, because GDP will then grow too. On the other hand, France and Germany are seeking to contain their health spending, which would reduce the average and leave the NHS with less than it might have expected. Mr Blairs pledge appears to assume that spending on private healthcare will remain the same, but will it? And whose calculations of EU GDP figures are being used? Different sets differ by fractions of a percentage, but even minuscule discrepancies translate into large sums of cash.

The NHS knows from hard experience always to look a gift horse in the mouth. Mr Blairs largesse will be no exception. But whatever the answers to the questions it raises, Mr Blair is to be applauded for refusing to be budged from the principle of funding the service through taxation. Siren voices bidding him otherwise have reached a crescendo reminiscent of the late 1980s.

Their solutions are illusory. A major increase in private provision would create deep divisions, and the assumption that it would automatically ease the burden on the NHS is a fallacious one.

Social insurance would introduce a more expensive and bureaucratic system in which costs threatened perpetually to escalate as surpluses of beds, staff and equipment accumulated.

Under either option, the public would soon rue the day they were persuaded to turn their back on the NHS.