The population history of London was the subject of the first major demographic treatise in English, John Graunt's Natural and political observations and conclusions made upon the bills of mortality, first published in 1662. Thus the London statistics have always been closely connected with the origins of historical demography in England. The bills of mortality consist of aggregate totals of baptisms and burials for the whole of London, compiled weekly from the individual Anglican parish registers by the Company of Parish Clerks to advise the city authorities of the onset of plague epidemics. The main series which now survives is of annual totals and these were used by Graunt. He explained that the object of his enquiry was:

Graunt was a relatively ordinary London tradesman, and he tried in his book to convey his understanding of what was happening in his native city during the first half of the seventeenth century. The book was published only three years before the last plague epidemic, and so it appeared at the end of the period for which its conclusions were valid.