As the apparent shortage of GPs worsens, the inevitable reaction will be to cast around for any under-used medical personnel who might be roped in to fill the growing gap.

Where might we look first?

I nominate health authority public health departments. Do they serve any useful purpose? Of course they do, but to what degree?

Is it really still necessary to employ large numbers of full-time highly qualified medics on work which could, 90 per cent of the time, be done by far less costly administrative staff? In some cases, it hardly needs doing at all.

Public health has an honourable history going back at least as far as the Public Health Act of 1848, when the fear of cholera led to the formation of a General Board of Health.

We can all salute the work of John Snow, the father of epidemiology, whose statistical analyses famously led to the discovery that the fount- of-all-cholera in London's Soho was a public water pump in Broad Street (although the story that he then removed its handle and ended the outbreak is apocryphal).

Who can fail to applaud those who framed the 1872 Public Health Act with its 342 sections on pure water, sewers, burials and the disposal of rubbish?

And who cannot be impressed by the enthusiasm which led to the compulsory vaccination of children against smallpox in 1853?

Immunisation campaigns against diphtheria, tetanus, polio, mumps and measles have transformed childhood, not only saving countless lives but removing the enormous burden of fear shouldered by young parents.

The environment has been much improved, too. Britain has been transformed since the Clean Air Act of 1956, which followed the smog-induced deaths of 4,000 people over four days in a London pea-souper.

Anyone seeking evidence of the success of public health medicine need look no further than their local reference library. Pick any annual report by the medical officers of health before 1900. Death in the first year of life was measured in hundreds per thousand, not tens.

Healthy working class adults who survived to the age of 60 were the exception.

Our remarkable longevity today is largely due to affluence and good public and environmental health. Neither wonder drugs nor surgeons' skills have made the greatest contribution to good health, but rather the combination of adequate food, clean water, clean air, dry homes and childhood immunisation, which led to death rates falling across the board long before the discovery of antibiotics and sulphonamides.

All other medical advances, however valuable, must come a poor second to public health initiatives.

But without a sudden outbreak of bubonic plague, public health doctors now have very little to do.

The Broad Street pump could only be discovered once. For a brief period when it looked as though AIDS would take on the proportions of a biblical plague, there was the possibility that public health might experience a renaissance, but that has proved a false dawn.

Anyone comparing today's annual public health reports with those from 100 years ago will be immediately struck by their blandness, their inevitable sameness and the desperate sense of trying to wring the last drops from an already bone-dry cloth.

Hardly any common communicable diseases have not been as good as beaten. Odd outbreaks are soon controlled, and any doctor - indeed almost any person - knows what public health measures need to be put in place to contain the problem. The big killers today are cancer and heart disease, killers of the old, not the young, and no public health measures in the world can prevent old age.

There is no plague, or epidemic, of coronary heart disease other than in the metaphorical sense. And even if cancer and heart disease can be delayed by lifestyle changes, such changes can now lead to only marginally improved life-expectancy.

Perhaps the sole major improvement to public health not yet implemented is the fluoridation of water supplies. But we no longer require specialist doctors to tell us that - the facts are there for all to see. That question is one of political will, not clinical knowledge.

Public health won its great victories many decades ago, and now trades on past glory. Its remaining functions - commissioning health education, collecting health statistics and reporting on them - could be carried out just as effectively by part-time honorary public health directors (perhaps by GPs working, say, one day per month).

They could be helped by a clerical assistant and a statistician rather than those heavily staffed and enormously expensive public health departments so beloved by health authorities.

And wouldn't it be marvellous if we could find a public health director brave enough to issue an annual report printed on just one side of A4 which said simply, 'Absolutely nothing has changed since last year, and of those problems that do exist there is very little of significant value which you or I can do about them.'

More important, given the reported shortage of 'real' doctors, at what point will the government decide that medical practitioners currently leading unproductive and unfulfilling lives in public health would be better employed treating real patients rather than having their undoubted talents going to waste at such great public expense?