Sinn Fein was once disparaged as the political wing of the IRA. It’s now on course to be the biggest party in both the north and south of the island.

With the UK’s exit from the European Union, the challenge of managing the Irish border as a source and a symbol of British-Irish difference became an international concern. The solution found in the UK-EU Withdrawal Agreement gives the Irish border a globally unique status.

That vote -- five years ago Wednesday -- was supposed to settle the United Kingdom's perennial neurosis over its relationship with Europe once and for all. It did nothing of the sort.

An expected snap election in Northern Ireland would become a mini-poll on post-Brexit trade arrangements.