July 5 this year will be the 60th birthday of the National Health Service. The NHS has come to occupy a place in the national psyche that is almost religious: every politician has to declaim, sooner or later, and often, “I believe in the NHS”, or face electoral limbo. Anyone putting forward serious criticism or suggesting change risks heartfelt disapproval, as if both our sole article of national faith and our most powerful repository of identity were being desecrated.

So it is hardly surprising that almost before the new year had begun both Gordon Brown and David Cameron had come forth with statements of impassioned commitment to the NHS. Brown got in first but his effort backfired hilariously with his comments about the rights and responsibilities of NHS patients seeking treatment; the media, in the absence of much news, headlined this as a threat to deny treatment to fatties and smokers – something that is often done already, but at which the prime minister was unwise to hint.

Cameron followed with his tribute to its founding idea of fairness for all. And tomorrow Brown is going to deliver what is inevitably called a “keynote speech”, rousingly entitled The Future of our NHS: Personal and Preventative. Since it can no longer be denied that all is not well with the NHS, both men are calling for something that their parties have discussed for several years – an NHS constitution.

Oddly enough it doesn’t have one; it has been the typical British muddle, based on a noble and impossible idea – comprehensive and equal treatment for all, free at the point of need.

I suppose a constitution might be a good idea, although personally I wouldn’t start from there. But the point is surely that any constitution will be quite useless unless those who write it are prepared to grasp several nettles which politicians have for decades found too painful to touch.

First is rationing. Nearly all of us now know that the NHS – the taxpayer – cannot afford to pay for all the treatments and drugs that are already available, still less for those that will be developed in the future.

The demand is going to be almost infinite; tax receipts are not. As more conditions become treatable and patients’ demands become more sophisticated, this problem will soon be a great deal worse.

Everyone knows this and most people admit it, except for politicians. Doctors and think tanks have been pressing the government to recognise it for years. The Institute for Public Policy Research reported in 2000 that the public would lose confidence in the NHS unless the government admitted that state healthcare must be rationed. Indeed it already is, one way and another.

For instance, Saga magazine and Populus have published a survey suggesting that one in six people over 50 had been denied treatment on grounds of cost. More than half the doctors replying to a survey in Doctor magazine said patients were suffering as a result of being denied treatments on grounds of cost. The chairman of NHS Alliance, which represents NHS trusts, commented that “rationing is the great unspoken reality”.

The other nettle that nobody wants to grasp is fairness, or to use that infuriating cant word, “equity”, which seems to conflate fairness and equality. Equal treatment for all is a first article of faith. However, it never has existed and never could, simply because doctors and nurses vary hugely in their abilities and experience. Even in the same hospital, two surgeons will have very different death rates, particularly in certain specialities. Patients, too, vary hugely in their ability to make the best use of services, right down to taking their medicine properly. All this is unfair, but unavoidably so.

Fairness and equality are at odds with what both Brown and Cameron say they want – local power, professional autonomy, devolution and diversity. That inevitably means having the notorious postcode lottery: one GP surgery or one hospital will do things differently from another. I am in favour of breaking up the monolithic power of the NHS altogether and having services offered by autonomous providers. But if you want a unitary NHS, it cannot be both localised and centralised. All this falls firmly into the category of “no easy answers”. That is precisely why it is high time to reconsider what exactly a National Health Service can realistically provide: most of the assumptions of 1948 are no longer relevant.

The idea of a free and universal service has been abandoned with the introduction of charges for dentistry, glasses and prescription. So has the principle that everyone is entitled to the same care – smokers, fat people, old people and heavy drinkers are already denied treatment and some candidates for dialysis or organ transplants inevitably find themselves at the bottom of the list.

If politicians were prepared to face these intractable problems, they might come up with unpleasant suggestions for rationing. I would start with the beginning and the end of life. It does not seem right to me that hugely expensive efforts are made to keep very premature babies alive only to lead a life of severe disability. Nor do I think it is right to strive to keep very old people alive; there was something to be said for pneumonia, “the old man’s friend”.

In the “national conversation” that Brown will undoubtedly call for tomorrow, I would mention that nearly half the NHS budget is spent on people aged over 64 and nearly a third on those over 74. These proportions are rising, according to Department of Health statistics for 2002-03 which I got in 2005; last week the department told me it could not give me updated figures as it does not keep them. I wonder why not. Are they considered too disturbing?

If I were elderly I hope I would consider my need for expensive cancer drugs less important than a young mother’s. Equally, although my default response is always for the freedom to smoke or hang-glide, I am entitled to feel differently if your freedom to give yourself coronary artery disease and diabetes competes with my child’s medical treatment. I regret to say Brown is right about that. These are all nasty thoughts, but without thinking them through the NHS will not survive many more birthdays.

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