In the case of a Brexit without an agreement
A referendum on Northern Ireland's withdrawal from the United Kingdom in the event of a Brexit without an agreement was again called for by Sinn Fein, the province's largest nationalist party.
In the last two years, following the Brexit referendum, in which a majority of Northern Irish people voted in favor of staying in the European Union, Sinn Fein has repeatedly called for a referendum on the secession of Northern Ireland and its union with Ireland.
Speaking in the Irish parliament in Dublin today, the party leader, Mary Lou McDonald, stressed that a naughty Brexit "would be catastrophic for the island" as it would "rupture our economy, social fabric and peace agreements". In such a case, that is, if London proceeds to leave the EU without an agreement, "Sinn Fein considers that a referendum on the unity of the island should be promoted as a matter of urgency and priority."