Imagine the following scenario: two patients with the same condition, lying next to each other in the same hospital ward. They see the same doctors, the same nurses, and have paid taxes all their lives to receive healthcare as and when they need it.

Yet their chances of survival may be very different, because one can afford to pay extra for the latest, most effective, drugs while the other cannot.

This is the dilemma of co-payments, currently being considered by the Government, which could mean patients paying privately to receive treatment to “top up” NHS care. Current guidelines aim to prevent co-payments, stating that “a patient cannot be both a private and an NHS patient for the treatment of one condition during a single visit to an NHS organisation”.

However, there is a lack of consistency about how this is interpreted. Some hospital doctors interpret “single visit” as a continuing episode of care while others stick to the letter of the rules. Most experts, including Alan Johnson, the Health Secretary, agree that such a situation is unsustainable.

Reform implies a number of practical problems, however; not least over what happens when a patient has benefited from privately funded treatment but runs out of money. Should the NHS then pick up the bill, or fund the cost of any extra care associated with privately funded medication?

Other questions arise over who should collect top-up payments, and when. The idea of bereaved relatives being sent a bill by local health trusts for drugs that a patient received in an NHS hospital before they died will be anathema to many supporters of the Bevanite health service.

In the new NHS constitution, ministers have reiterated their commitment to a service that is “based on clinical need, not an individual’s ability to pay”.

Of course, there are already some exceptions - some patients may already benefit from private medical insurance or be used to paying for dentistry, prescriptions or diagnostic tests.

But the pressure for change has come from a growing number of cancer sufferers who have been seeking to buy the latest drugs that are not yet provided by the NHS or have been rejected as not cost-effective, given the limited resources of a tax-funded system. These patients will already have appealed in vain to local health authorities.

At present the notion of co-payments is limited to such cancer drugs, capable of providing a few extra months of life at a cost of thousands of pounds, and often considered only as a last resort. But many working in the NHS consider the debate to represent the thin end of the wedge.

Cancer is becoming more of a chronic disease than a swift death sentence. Given the demands of an ageing population and rising drugs costs, money will have to come from somewhere.

Ministers and the pharmaceutical industry may yet find a middle way. Voters, however, will have to decide whether they can stomach paying more taxes for comprehensive care or be prepared to accept second-best.

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