Britain's Home Office, the government department responsible for border control and immigration, has admitted it has not consulted any external experts on the effect of Brexit on the Irish Border.
The Border, and the wider implications for the Republic of Britain's exit from the European Union, is one of the three points of negotiation between the EU and UK government (the others are free movement of people and the amount of money Britain will owe the union after the divorce).
Each needs to be settled before the EU will entertain negotiating a trade deal with the UK outside the union.
Despite the border being a key issue in negotiations, the Home Office has not sought any advice from experts on the potential impact of Brexit on Irish citizens living in Britain or Northern Ireland.
The Home Office's admission – made in response to a Freedom of Information Act request lodged by the investigative website theferret.scot – has been described as "shocking" by experts on both sides of the Border.
SDLP leader Colum Eastwood accused the British government of "leaving us behind" and called on the Irish Government to "stand up" for the interests of northern nationalists.
While the Border is one of the three main issues to be negotiated, both the British and Irish governments have insisted that the Common Travel Area will remain in place after Brexit and that disruption to Irish citizens will be minimal.
But concerns have been raised that Brexit could throw up unexpected problems around the Border and the status of Irish citizens in Britain, particularly if the UK adopts a different immigration policy to the rest of the European Union. More than 380,000 Irish-born people live in Britain.
Fears have also been growing among Irish passport holders living in Northern Ireland. Earlier this month, the UK government refused a visa application from the husband of a Co Derry woman who refused to describe herself as British.
The UK Home Office has not consulted any experts about whether Brexit could affect the status of those people born and resident in Northern Ireland who choose to hold an Irish passport only under the Good Friday Agreement. The office has also not spoken to any outside sources about the potential impact of Brexit on immigration controls and smuggling at the Irish Border.
"They think they have all the expertise in-house. It's quite shocking," said Katy Hayward, senior lecturer in Senator George J Mitchell Institute for Global Peace, Security and Justice, at Queen's University Belfast.
“Given that we don’t have devolution in Northern Ireland and the problems we have here, you would have thought it would be all the more reason to draw on expertise, particularly in relation to citizenship, to smuggling. These are key issues,” she said.
Mr Eastwood said it shows that “this British government just doesn’t care about the effect of Brexit on the North”.
“Brexit is the biggest constitutional and economic challenge to face this island since partition.
“Despite their claims that Northern Ireland is a priority, it’s clear from the absolute vacuum of preparatory work undertaken by the Home Office that this British government just doesn’t care about the effect of Brexit on the North,” Mr Eastwood said.
“This underscores the critical need for an Executive to make the case for our unique circumstances as part of the negotiations. And it further emphasises the need for the Irish Government to stand up for our interests when the British government has clearly left us behind.”
‘Not a foreign country’
The Home Office told The Irish Times that it believes that Irish citizens were “not foreign” under UK law as the Ireland Act 1949 is still in force. The Act states that “the Republic of Ireland is not a foreign country for the purposes of any law in force in any part of the United Kingdom”.
But Bernard Ryan, professor of migration law at the University of Leicester, said the 1949 Act was "completely out of time" and would require updating to guarantee Irish citizens' rights.
The UK government's Brexit White Paper promises that the Irish Border will be "as seamless and as frictionless as possible". Brexit secretary David Davis has repeatedly mentioned trusted trader schemes, automatic number plate recognition and pretagged containers as possible solutions to the Irish Border problem.
But earlier this month, the Minister for Foreign Affairs Simon Coveney said that such technical solutions were "not going to work" and that free movement of goods, people and services across the Border was essential to peace and stability.
The introduction of customs checks or other forms of border control after Brexit could open a debate about whether maintaining the Common Travel Area is in Ireland's best interests, says Ben Tonra, professor of European Foreign, Security and Defence Policy at UCD.
“If the Common Travel Area is going to be so attenuated that it doesn’t really work anymore and the British government is demanding checks at the Irish border, then it might be time to do a proper cost-benefit analysis of the costs of the Common Travel Area versus the benefits of Schengen.”
The UK Home Office said that although it had not sought expert advice information already in the public domain had been examined.
“Irish citizens residing in the UK will not need to apply for settled status to protect their entitlements and we will continue to uphold the rights of people of Northern Ireland to be able to identify as British or Irish, or both, and to hold citizenship accordingly,” a Home Office spokesperson said.