Religious Demographics since 1742

In recent discussions about the 1926 Census, there was a consideration about whether the population of Protestants has declined since the foundation of the Free State. I thought it would be interesting to trace the proportion of the population in each religion across three centuries in our area. By looking at proportions, we don’t need to do complicated maths to take population decline (and growth) into account, we can just look at the ratio of one to the other. The graph below shows the findings. Some serious footnotes apply – see below. I’d be interested on people’s views. My take on it is that the proportions have stayed reasonably constant through the 19th century, with the Protestant proportion falling slightly to a new level in the 20th century. The earlier data needs a pinch of salt, but perhaps the shift from 18th to 19th century also saw a slight drop in Protestant numbers.



  1. 1742 and 1766 data comes from two eighteenth century surveys described here. They were based on number of families and tended to underestimate the number of Catholics.
  2. The 1834 data is from a religious population Census in the context of education. This may have over-estimated the number of Protestants.
  3. The population of Catholics from 1861 – 1911 does not include the number of residents in the Glencree Reformatory. The value is corrected using a weighting of the 1851 townland of Aurora (i.e. before the Reformatory opened).
  4. The 1926, 2006 and 2011 Census are based on the sum of the Powerscourt and Enniskerry District Electoral Divisions, which together make up the previous electoral division of Powerscourt Parish.
  5. The 2006 and 2011 data returns number of Roman Catholics and number of other religions. The “Other” value was taken to the number of Protestants.
  6. All data excludes other religions (Methodists, Presbyterians, etc) who were very low in number in the nineteenth century. The 21st century data excludes atheists and non-declared religions.