One of the most striking features of unorthodox medicine—variously described as quackery, irregular medicine, fringe medicine, or complementary and alternative medicine (CAM)—has been its ability to survive for centuries in a very wide variety of forms. Although it has changed enormously with the passage of time, unorthodox medicine has always has been a rich source of disputes, claims and counter-claims, and accusations of fraud. One might expect that unorthodox medicine as a whole would have diminished as a result of the spectacular advances in regular medicine during the second half of the twentieth century, but that does not seem to be the case. In fact we will never really know how many people in the past consulted unorthodox practitioners instead of, or in addition to, consulting the orthodox; we don't even know today. But we do know that before the mid-nineteenth century the irregular practitioners for whom the derogatory term ‘quacks’ is appropriate, were used by a large proportion of the population.

Most of these pre-1850 quacks tended to specialize. Some were bone-setters, others claimed to cure venereal disease without the use of mercury. A ‘Dr’ Taylor of Beverley in Gloucester arranged to attend regularly at three public houses to which patients only had to send their urine and he would tell at once whether they were curable or not.