In 1921 the British government employed crude sectarian arithmetic to carve out six counties from the rest of Ireland. Its aim was to create a Protestant-dominated jurisdiction in the north of Ireland that supported remaining part of the United Kingdom.
The centenary events planned for 2021 presented an opportunity for Northern Ireland to show a decidedly different aspect, marking itself out as a place where power is shared and diversity is cherished. Brexit has made that prospect much less likely. The vote to leave the European Union has eroded much of the bedrock of the 1998 Good Friday Agreement, hardened the political divide in the province and dealt a significant blow to British-Irish relations.