IRELAND should draw up an equivalent of the white paper which set out the case for Scottish independence in anticipation of a border poll getting underway in the next decade, a leading constitutional expert has said.

Brendan O’Leary, professor of political science at the University of Pennsylvania, said before a referendum voters would have to be clear on what a united Ireland would look like – in contrast to the “chaos” which was triggered by Brexit.

The comments come ahead of Boris Johnson visiting Northern Ireland tomorrow, amid a political crisis sparked by post-Brexit trading arrangements.

Sinn Fein made history in the Northern Ireland assembly election by emerging as the largest party for the first time, and has called for debate on a united Ireland.

READ MORE: Sinn Fein's Mary Lou McDonald says Boris Johnson ‘in cahoots’ with DUP

But the immediate future is one of political uncertainty, with the new assembly left unable to function after the DUP blocked the election of a Speaker last week.

DUP leader, Sir Jeffrey Donaldson, has insisted the move is sending a “clear message” to the EU and the UK Government about resolving issues with the Northern Ireland protocol.

O’Leary, who has been a political and constitutional advisor to the UN, the EU and the governments of the UK and Ireland, said he believed the Northern Ireland Secretary – who holds the power to call a border poll – was likely to start thinking about it around 2030.

Speaking at an expert panel event held by the Centre on Constitutional Change, he said: “The reason I take that view is not because I think demography is destiny, but nevertheless it will be the case in 2030 that in every age cohort except possibly the over 85s, there will be a non-Protestant majority.

“So at that juncture, unless there is massive emigration or massive immigration into Northern Ireland between 2011 and now, that we haven’t noticed and some massive migratory change in the future, the fate of Northern Ireland will be in the hands of non-Protestants for the first time.”

He added: “Irish reunification is not inevitable, but it is plausible and possible in ways that were not true before it is plausible because the Republic of Ireland is a dramatic institutional and economic success.

“That can’t be said of Northern Ireland, nor can it be said of the United Kingdom, which is an institutional mess as a consequence of Brexit.”

O’Leary (below) was part of a working group to examine how any future referendums on Northern Ireland would be conducted, which published its final report in 2021.

The National:

He said the group of independent scholars who participated had a mix of those with “soft” nationalist and Unionist positions – but all agreed that any vote would ideally be “nothing like the Brexit referendum”.

“If you want to characterise the Brexit referendum, it was one in which there was choice between the status quo and an undefined alternative,” he said.

“That was partly the result of [David] Cameron’s own decision, he wanted to polarise the choice between safety first for the UK and chaos.

“Well, chaos won. And chaos then meant there was a constant debate about what the meaning of the referendum was.

“So most of us attached this referendum group agreed that in a properly prepared referendum it would be clear what the question was, it would be clear what voting for a united Ireland would mean.

“And that would mean decisions would have to be made in advance – would it mean the dissolution of Northern Ireland, would it mean the retention of a devolved Northern Ireland inside a united Ireland, what would be the arrangements on the economy, policing, social service, on the health service and so on?”

O’Leary said it was possible for this to be done by pointing to the example of the SNP’s white paper on Scotland’s Future which was published in advance of the 2014 independence vote.

He suggested something similar “must be prepared” over the next decade by a unification unit in the Republic of Ireland government, which Sinn Fein has said it intends to set up.

“Unification would have momentous consequences for the Republic and all those things should be clear in advance,” he added.

Last week speaking after the DUP refused to support the election of a Speaker, party leader Donaldson said the Northern Ireland protocol was “undermining political stability, damaging the agreements that have formed the basis of political progress made in Northern Ireland, to our economy, contributing to the cost-of-living crisis.”

He called for the EU to take action and also said “the ball is firmly at the foot of the [UK] Government.”

The Prime Minister has warned the UK could ditch the protocol unless Brussels agrees to major changes but that has raised the prospect of a trade war with the EU, which in turn has warned it will respond with retaliatory measures if the UK acts unilaterally.

Clare Rice, a postdoctoral researcher based at the University of Liverpool, who also spoke at the expert event last Thursday, said the issue was resting in Boris Johnson’s hands.

But she added: “It’s domestically convenient for him at this point to ramp up the tensions with the European Union.

“He has faced his own bashing at the ballot box with the local council elections that were held, he is facing a lot of flack within his own party, particularly with regard to the protocol and a lot of pressure that he should have taken more decisive action before now.”

READ MORE: How council tax reform could boost support for Scottish independence

But she said it wasn’t clear what Johnson intended to achieve by raising tensions with the EU over the issue.

“I think we are in an extremely difficult situation politically in Northern Ireland, where we are looking to the Prime Minister to give that nod, to give that direction,” she said.

“Or just to give something that will act as least as an encouragement, or just something the DUP is able to sell to its voter base or it is able to sell itself full stop – it can say look we achieved this, that will do for now and we will get back around the table.

“That is not happening – the one person who should be at the centre of all of this at the moment is Boris Johnson, the Prime Minister.”