Catholic Church in Ireland
In the 2016 Irish census 78.3% of the population identified as Catholic in Ireland; numbering approximately 3.7 million people. Unlike Catholics in the United States, Ireland has seen a significant decline from the 84.2% who identified as Catholic in the 2011 census.
Catholic Church in England and Wales
Migration from Ireland in the 19th and 20th centuries and more recent Eastern European migration have significantly increased the numbers of Catholics in England and Wales, although Pew Research data and stats of 2018 point to other factors at work. According to Pew researchers, 19% of UK adults identify as Catholic, nearly doubling the Catholic population. While figures for England and Wales alone are difficult to estimate, the ethnic make-up of the Catholic population in the UK (which includes Northern Irish as British) was, at least in 2008, as follows :