Practically all the facts and figures given below require detailed qualification in some respect or other. The principal qualifications that are needed relate to: (i) the structure of the population at risk (age, sex, occupation, geographical selection, etc.); (ii) the extent to which these populations are ‘live’ or ‘dead’ on doctors’ lists; (iii) bias in the selection and sampling of practices; (iv) bias in the movement between the private and public sectors of general practice; (v) the extent to which pre-1948 figures of visits and surgery attendances among private patients were deflated by the fact that the poor law, voluntary dispensaries and various public services carried a disproportionate number of ‘bad risks’; (vi) the definition of a general practitioner, general practice, medical consultation, surgery attendance, domiciliary visit, patient, prescription and other terms; (vii) seasonal variations in population structure and services rendered; (viii) changes in the pattern of disease and fluctuations in epidemics of infectious disease; (ix) errors in record-keeping by doctors; (x) changes in the use by doctors of ancillary and other services (district nurses, health visitors, general practitioner assistants, hospital facilities, rota systems, locums, secretaries, etc.); (xi) changes in the use made by patients of chemists’ shops and self-medication.

A general practitioner's work is usually measured in terms of medical consultations per person per year. These are normally broken down into surgery attendances (A) and home visits (V).

The most comprehensive and relatively reliable post-1948 figures are those provided by the Government's Social Survey from its ‘Sickness Survey’ of a representative sample of the adult population of England and Wales. This ran from 1945 to March 1952 when it was suspended on grounds of economy. From the mass of information provided the most important figures are those for 1949-50 when the same population base was used. It is possible that this was the period of peak demand under the National Health Service; prescription and other charges were introduced subsequently. The total consultation rate (including those with all doctors at hospitals and clinics) for both sexes at all ages over sixteen was 5.46 per person per year. Excluding consultations at hospitals and clinics the rate was 4.62 (attendances 3.00, visits 1.62). Because, however, of the substantially higher rates for women and persons aged over sixty-five these figures are not comparable with pre-1948 National Health Insurance experience.