MercoPress. South Atlantic News Agency

Four years since Brexit, Northern Ireland is led by a Sinn Féin First Minister, Michelle O'Neill.

A Sinn Féin first minister Michelle O'Neill, would be a landmark moment - the party aspires one day to unite with the Republic of Ireland.

BBC has recalled that at 23:00 GMT on 31 January 2020 (midnight Brussels time, as January became February there), the EU shrank, the UK was out. Four years later, as the latest solution to one of the knottiest of consequences of Brexit, or at least the flavor of Brexit chosen, is revealed.

The UK government has published what is known as a Command Paper setting out the detail of the changes to Northern Ireland's post-Brexit arrangements that have tempted the Democratic Unionists, or at least most of them, to go back into power-sharing devolved government.

This is 80 pages that is meant to read as a deluge of reassurance - particularly for the Democratic Unionist Party. Over and over again is the central claim that Northern Ireland must be “an indivisible part of the UK's economic union”.

The document acknowledges the initial Brexit model didn't work for Northern Ireland and the attempted improvement, the Windsor Framework, didn't go far enough either.

The government has received a lot of praise in the Commons, but there are jabs of criticism and skepticism too. And it is clear that the consequences of Brexit will remain a fault line in Northern Ireland's politics and economics, even with a functioning executive and Northern Ireland Assembly.

This Thursday, the changes in the law required will happen, via what are known as Statutory Instruments. Once they pass, as they will, attention will switch back to Belfast. And the prospect not just of restored devolution, functioning government for Northern Ireland, but a Sinn Féin First Minister, Michelle O'Neill.

A Sinn Féin first minister would be a landmark moment - the party aspires one day to unite with the Republic of Ireland.

And take a look at the Republic - Sinn Féin surged forward at the last general election and opinion poll numbers for them, while down recently, suggest they are the most popular political party in Ireland, with an election expected in the next year or so.

Yes, Northern Ireland's first and deputy first ministers have equal legal powers, and one of them can't make any decisions without the agreement of the other. But one job title has the word “deputy” in it. And the other does not.

The assembly leader of the largest party becomes the first minister, and Sinn Féin won more seats than any other party - for the first time - in the devolved elections in Northern Ireland in May 2022.

It will be a moment heavy with history when Michelle O'Neill becomes first minister.