As factors such as the cause of death and the incidence of diseases vary in different social strata, the Registrar-General evolved the following social classification, which has now been in official use for many years:
Class I
Professional occupations, such as lawyers, clergymen, and commissioned officers in the Armed Forces.
Class II
Intermediate occupations, such as teachers, managers and nurses.
Class III
N: non-manual – for example, clerical workers.
Class III
M: skilled manual occupations such as miners and bricklayers.
Class IV
Partly skilled occupations, such as agricultural workers.
Class V
Unskilled occupations, such as building labourers.