In 1944 the Royal Commission on Population was set up in order to determine the probable consequences of population trends then current. In order to do this they prepared a range of sixteen separate population projections for Great Britain based on various combinations of assumptions as to mortality, fertility (and marriage), and migration. The method used, in which each component of population change i.e. birth, death and migration receives separate treatment, is generally known as the component method. This distinguishes it from cruder methods based on the assumption that the total numbers in a population follow some mathematical formula.

Since the Royal Commission reported, this method has continued to be used in preparing what may perhaps be described as the ‘official’ projections of the population of England and Wales.