Catholics outnumber Protestants in Northern Ireland for the first time, a demographic milestone for a state that was designed a century ago to have a permanent Protestant majority.
Results from the 2021 census released on Thursday showed that 45.7% of inhabitants are Catholic or from a Catholic background compared with 43.48% from Protestant or other Christian backgrounds.
The 2011 census figures were 45% Catholic and 48% Protestant.
Neither bloc is a majority.
The demographic tilt was expected but will still deliver a psychological hit to unionists, who for decades relied on a supposedly impregnable Protestant majority to safeguard Northern Ireland’s position in the UK.
Diarmaid Ferriter, a historian and author, said: “It’s been long coming. They have already witnessed the loss of their political supremacy. Seeing the loss of their numerical supremacy is another blow.”
Higher birth rates among Catholics gradually closed the gap, a closely watched metric since they tended to identify as Irish while Protestants tended to identify as British. But religious background and political identity no longer automatically transferred to voting patterns, Ferriter said. “So much is blurred now.”
In recent elections support for nationalist and unionist parties plateaued at around 40% for each side, leaving 20% of voters in the middle who are non-aligned and reject traditional sectarian labels. Opinion polls consistently show more people favour staying in the UK – citing taxes and the NHS, among other reasons – than uniting with Ireland.
However. the census, the first since Brexit, showed a loosening of British identity. Some 31.86% identified as British only, 29.13% identified as Irish only and 19.78% as Northern Irish only. In 2011 the figures were 40% British only, 25% Irish only and 21% Northern Irish only.
The census, published by the Northern Ireland Statistics and Research Agency, also showed Northern Ireland with its highest population, 1.9 million people, a 5% increase from 2011. It is ageing, with the number of people aged over 65 increasing by nearly 25%.
The data on religious background – a stark contrast to the state’s foundation in 1921, when Britain cleaved six counties from the rest of Ireland to create an entity with a two-thirds Protestant majority – comes at a fraught time for unionism. A post-Brexit Irish Sea border has put trade barriers between Northern Ireland and Great Britain. In May’s assembly election, Sinn Féin overtook the Democratic Unionist party as Northern Ireland’s largest party, boosting its calls for a referendum on Irish unity.
Duncan Morrow, a politics professor at Ulster University, said: “The state was set up to put a protective ring around Protestants. You can’t take away from the symbolic significance of this change.”
In a referendum, Northern Ireland’s fate may rest with centrist voters who defy easy political categorisation, with many feeling Northern Irish as opposed to Irish or British, Morrow said. Young people were keenest on Irish unity, he added. “It’s a ticking clock.”
Patricia McBride, a spokesperson for Ireland’s Future, a group that promotes a border poll, said religious background and national identity would not necessarily determine how people would vote. Taxation, public services and other bread and butter issues could be decisive, she added.
“People are much more likely to question whether or not they are financially better off. It’s not as simple as voting with the heart, people will be voting with the head as well,” she said.