Ever since Britain stunned the world, in June 2016 with a referendum setting Brexit in motion, the future of the Irish border has hovered over the proceedings as the single most intractable problem and the element most liable to yield disaster. How can Britain leave Europe without enforcing the demarcation? Yet a hard border could reignite the hostilities that long plagued communities on both sides. It could impede vibrant trade across the border, which has fostered peace.
For the last three decades of the 20th century, the border was militarized. Northern Ireland was besieged with conflict between predominantly Catholic communities that favored joining the Republic and largely Protestant loyalists of the British crown. People along the border were accustomed to violence and fear.
The Troubles, as this period was known, officially ended with the signing of the Good Friday Agreement in 1998. Among the provisions of the truce was a shared understanding that people and goods must be allowed to move freely across the border. Trade would become a source of cross-border cooperation that would lift fortunes.
Last year, Northern Ireland and the Republic traded goods worth more than 3.2 billion euros (about $3.6 billion), according to official figures. The Republic sends meat, pharmaceuticals and whiskey north. Northern Ireland sends large volumes of dairy products, live animals and animal feed.
From where Mr. McNamee sits — at the kitchen table in the farmhouse where he was born and raised — the return of a hard border would put all of this progress at risk.