The last life table for the Administrative County of London was prepared by Mr King from the census population of 1911 and the deaths in 1910, 1911, 1912, and published in Part I of the Supplement to the 75th Annual Report of the Registrar-General, 1914. The national life tables (No. 9), prepared by Sir Alfred Watson after the census of 1921, included one for “Greater London,” the boundaries of which extend considerably beyond the County Council area and enclose the range of jurisdiction of the Metropolitan Police, so that this table is not geographically comparable with Mr King's 1911 table. The object of the present study was a comparison between the extended method of Mr King and the shorter ones of Drs Brownlee and Snow, to see whether the methods gave comparable results as regards the expectation of life, the question with which the public health worker is mainly concerned. As an example I selected the County of London (census population for 1921, deaths in 1920, 1921, and 1922) as affording, at the same time, an opportunity of making a table comparable with that which Mr King prepared for 1911. Drs Brownlee and Snow have already shown that their methods gave very satisfactory results as judged by the older life tables of this country. This paper will show that similar results have, in the main, been obtained as regards the 1921 experience.