From 1799 to 1801 he edited the Commercial, Agricultural, and Manufactures' Magazine which published his article "On ascertaining the population" in 1800.

An earlier version of this paper entitled "Thoughts on the Utility and Facility of a general enumeration of the People of the British Empire".

Rickman was instrumental in carrying out the first four censuses of Great Britain, including not only a population count, but also the collection and analysis of parish register returns.

Following Abbot's election to the post of Speaker of the House of Commons in February 1802, Rickman took the post of Speaker's Secretary, which he held until July 1814 when he was appointed Second Clerk Assistant at the Table of the House of Commons.

[5] The subtitle to Orlo William's biography of Rickman: Lamb's Friend the Census Taker under-emphasises his extensive parliamentary work.