The annual agricultural returns, known as the June Returns, have long been used by geographers and historians as a basis for studying the longterm trends in English and Welsh agriculture since 1866. It was in that year that the first British agricultural census was introduced and subsequently systematised. Twenty years earlier the collection of annually aggregated agricultural data was pioneered in Ireland. It began in 1847, in the wake of the onset of the Great Famine, but before the full trauma of that event had been played out. Indeed several years earlier an agricultural census of sorts was attached to the 1841 population census. This early census recorded livestock numbers at the national, provincial and county levels, though some of those data are suspected of underestimation. This is certainly the case with the cattle numbers, and also with the pig numbers if 1841 is to be regarded as a contemporary ‘average year’. The 1841 census also gave an appraisal of landholding distribution, across space, and also by size categories under four main landholding size groups. Some of these data are the subject of very severe criticism; there is the suspicion that the enumerators of the census used a mixture of statute and Irish acres, where the latter is 1.62 times the size of the former. Nevertheless, the 1841 census, in association with the 1845 Poor Law Commissioners' Report is widely used as a pre-Famine benchmark in the study of Irish agriculture. If census enumeration is a learning-by-doing exercise then the post-Famine agricultural statistics when they appeared were reputedly ‘free from major error’.