Ireland was partitioned in 1921. The crisis over food supplies in Northern Ireland is the result of a second partition of Ireland in a hundred years

The first time the island of Ireland was artificially split it was hardline Catholic clericalist nationalists entering into an unspoken and unholy alliance with their opposite numbers – hardline Protestant-identity unionists – to divide the island of Ireland to their mutual political and economic advantage. The campaign for autonomous status that would allow Ireland to control its own destiny separate from London and the mainland of Great Britain had dominated politics for much of the nineteenth century and into the early twentieth century – dividing both the Tory and the Liberal parties.

It was commonplace in post-1918 Europe to see borders redrawn but no one had ever imagined that could be applied to the United Kingdom. The leaders of the Irish Parliamentary Party demanding Home Rule for Ireland included Protestants such as Charles Stewart Parnell and Catholics such as John Redmond. The idea of splitting Ireland apart and creating at Stormont what the Ulster Unionist leader, Sir James Craig, called a “Protestant Parliament for a Protestant State” played no part in Home Rule campaigning and voting until the First World War changed all the rules.