The Irish census of 1841, the third in a decennial series, introduced many new features which changed that operation from a mere headcount of people to a social survey. The chief architect of this development was census commissioner Thomas A. Larcom, a soldier by profession, who, as an officer of the Royal Engineers was superintendent of the Dublin Office of the Ordnance Survey. Much more than an able organiser and a skilful engineer, he became an antiquarian and a social historian who planned to make the Ordnance Survey a basis for the collection of comprehensive information about every part of the country.

His subsequent work on the Census was distinguished as much by its ingenuity and thoroughness of compilation as by the originality of the overall plan. He developed a special interest in maps and used his experience to illustrate the census results for density of population and also for some of the new features introduced, especially quality of housing and level of literacy. At that time Ireland did not have an official registration system for births, marriages and deaths, so extra details were collected in the census, at household level, to enable valuable analyses of vital events. An impressive use of cross classification was another feature of the Census Report.

Health problems prevented him from presiding over the 1851 Population Census but Larcom had another important involvement in official statistics - the inauguration of an annual collection of agricultural statistics, commencing in 1847, at the height of the Great Famine. In that year he was one of the founder member of the Statistical and Social Inquiry Society of Ireland.

His permanent secondment to civil administration brought Sir Thomas in 1853 to the position of Under Secretary for Ireland-the highest government official in the Irish administration.

Keywords: Ireland; Census; Survey; Social

Biography: Director General, Central Statistics Office, Ireland, for years 1966 to 1991