Hampshire family, was incumbent of Newburn at this time, and, after holding other livings, retired in his old age to Christchurch, Hampshire, where he died in 1809. John was sent in 1781 to the grammar school at Guildford, and in 1788 to Magdalen College, Oxford. He was afterwards at Lincoln College, whence he graduated B.A. in 1792. He conducted for some time the ‘Commercial, Agricultural, and Manufacturer's Magazine.’ In 1796 he wrote a paper to show that it would be easy and useful to take a census of the population. The manuscript was shown to Charles Abbot (afterwards Lord Colchester) [q. v.] by George Rose, M.P. for Christchurch. Abbot took Rickman for his secretary, and employed him in preparing the first census act, introduced in December 1800. When Abbot became chief secretary for Ireland in 1801, Rickman went with him to Dublin, and was made deputy keeper of the privy seal. He refused a permanent appointment in Ireland, and when Abbot became speaker in February 1802, Rickman continued to be his secretary, and settled in London. In July 1814 he was appointed second clerk assistant at the table of the House of Commons, and in 1820 clerk assistant, a position which he held till his death.
Rickman was an active official, prepared in 1818 a useful index to the statutes for the use of the House of Commons, and helped to form and arrange the library. He became chiefly conspicuous, however, for his labours upon the census. He devised the methods to be employed, and prepared the reports which were published in 1801, 1811, 1821, and 1831. A folio volume gave the abstracts of returns upon each of the first three occasions, and three folio volumes were published upon the census of 1831, besides a preparatory volume which was produced very rapidly in December 1831 with a view to the approaching Reform Bill. Rickman, besides arranging the abstracts of the returns and of the reports made by the clergy upon the parish registers, contributed many notes upon the results shown by the census, and made elaborate calculations as to the population of preceding periods. The results of his last researches are given in the preface to the census returns of 1841. Rickman had been employed upon the bill for that census, but died before the work was done. He became a recognised authority in these inquiries, receiving five hundred guineas for each census, which, however, included payment for other labours. He prepared annual abstracts of poor-law returns (1816–36), and made reports upon education (1833–5), Scottish education (1837), church rates (1838), and local taxation (1839).
Besides pursuing these labours, he acted from 1803 as secretary to the commissions for making roads and bridges in Scotland, and for constructing the Caledonian canal, and in 1823 was nominated to a commission for building churches in the highlands and islands of Scotland. Rickman had made the acquaintance of Southey at Burton, near Christchurch, where they were both staying in 1797. They formed a lasting friendship, and while in Dublin Rickman procured Southey's appointment as secretary to Isaac Corry [q. v.] They corresponded ever afterwards, and Southey always stayed with his friend when in London. In 1800 he was introduced to Lamb, who describes him characteristically in a letter to Manning (Letters, ed. Ainger, i. 145–6). Southey gives a similar description in a letter to Landor (Life and Correspondence, iii. 216). He was so careless in dress as to have been taken by the press-gang for a common tramp, but was heartily respected by his friends for his shrewd sense and wide knowledge; he was a fair scholar, but cared little for poetry; was quick in taking a joke, as Lamb testifies, and ‘the finest fellow,’ according to the same authority, ‘to drop in a' nights’ just when he was wanted. He made a tour with Southey and (Sir) Henry Taylor to Holland, in 1806. Southey's letters state that Rickman was a man of wide knowledge of literature. His Scottish commissions led him to form an intimate friendship with Telford the engineer; and he persuaded Telford to write an autobiography, which he published with notes in 1838, after the author's death. Sharon Turner, another friend, wrote to his son (‘Life’ in Gent. Mag.) that he was ‘not a man of genius,’ but singularly solid and sound; rather stern at times, and difficult to classify as a politician, because he liked to criticise all sides independently. He seems, however, to have sympathised with Southey's conservatism, and with his hatred of Malthus and the economists. Rickman, on 30 Oct. 1805, married Susannah, daughter of Joseph Postlethwaite of Harting, Sussex. She died on 12 May 1836. Rickman died of an affection of the throat on 11 Aug. 1840. He left a son and two daughters, and was buried with his wife in St. Margaret's, Westminster.
Rickman published an anonymous pamphlet on the poor laws in 1832, upon poor laws in Ireland in 1833, and a pamphlet upon the ‘Historical Curiosities relating to St. Margaret's Church’ in 1837. He also wrote
