Were it not for the subtle change in the road surface and the abrupt disappearance of the bilingual signs after the bridge on the river Blackwater, the border between the village of Emyvale in north Co Monaghan and Aughnacloy, on the Co Tyrone side, would be easy to miss.

Yet invisible though it may have become, this frontier looms large in the memory of anyone old enough to remember the darkest days of the Troubles. Then, the heavily fortified Emyvale-Aughnacloy crossing was the only official route between Monaghan and Tyrone.

A customs post led to a British army checkpoint, where vehicle inspections would leave a long tailback snaking back along the country roads. Overnight, the militarisation of the Border virtually cut off the two neighbouring communities.

"I grew up here, and I was probably south of the Border less than a handful of times in my childhood," says Stephen Salley, an Aughnacloy-based architect. Unlike many locals, he had no relatives on the other side of the Border, and through a combination of the hassle of having to queue for half an hour and a sense that going south was "a risky thing to do", he and his family rarely ventured south.

“For me, growing up as a unionist, I had no need to go across. It was a fence I didn’t have to cross . . . That feels like something was stolen from me. It wasn’t until I started working that I’d be across.”

When the Republic's economy surged on the back of a development boom in the mid-2000s, 40-45 per cent of Salley's business was south of the border. Today, like many in Aughnacloy, he is buying fuel and doing some of his shopping on the southern side. His car radio is tuned mostly to Today FM, and RTÉ television is frequently on at home.

The traffic goes both ways: shopkeepers in Aughnacloy say about 40 per cent of purchases are paid for in euro – largely as a result of the daily flow of shoppers from villages on the southern side and drivers taking a pit stop on the long journey between Dublin and Donegal.

Partition

Many people cross the Border each day to work; students from Monaghan work part-time at the local SuperValu and the village's restaurants. Carmel Hayde, who is originally from Cashel, Co Tipperary, and has been running the Clarins counter at the local pharmacy for years, says she sees as many southern customers as Northerners.

“This town suffered enormously through partition,” Salley says. “Now that’s maybe not politically acceptable to a lot of people, but that’s the reality. It was a small town. Half its hinterland was cut off by the Border . . . As the Troubles developed, people became more isolated, more separated. The last 20 years has seen that dilute again.”

Developing community relations in Aughnacloy remains a work in progress. Schooling is still segregated, and the village’s annual festival is held in a marquee in a field so as to avoid having to choose a venue associated with the Catholic or Protestant community.

The fall-off in cross-Border commerce hit Border communities hard, but the psychological effects of the separation went deeper. From 2012 to 2014, as part of a European Union-funded project called Border Roads Memories, a team of researchers interviewed hundreds of people who lived on either side of the Border during the Troubles. The testimony they gathered, says Ciara King, research officer on the project, drove home the "lasting effect it had on people, how hurt people were".

“People got segregated when it became too difficult to meet up,” she says. “Friendships were lost. It took quite a while to build that up again, and it’s still a work in progress for the younger generations who never knew their neighbours on the other side of the Border.”

As the countdown begins to the referendum on the United Kingdom’s EU membership on June 23rd, Aughnacloy is increasingly preoccupied with the prospect of another change in cross-Border relationships.

If the UK votes to leave, this frontier will be the only land border between the UK and the EU, raising the possibility that some form of controls could be reinstated. Secretary of State for Northern Ireland Theresa Villiers, who is campaigning on the Leave side, claims that, in the event of a Brexit, the Border would remain as "free-flowing" as it is today.

But this has been contradicted by the governments in Dublin and London, which have left open the possibility of new controls being introduced. In Amsterdam in January, Taoiseach Enda Kenny said: “If Britain were to leave, we would be looking at Border controls in Ireland, despite the fact that we have a Common Travel Area.” That view has been echoed in London, where a report by the British government cabinet office in March warned that, if the UK left the EU’s customs union, “it would be necessary to impose customs checks on the movement of goods across the Border. Questions would also need to be answered about the Common Travel Area which covers the movement of people.”

Although security and customs checks have operated along the Border at different times since partition, Irish and British citizens have, since the establishment of the Free State in 1922, had the automatic right to travel between the two jurisdictions without passports.

This openness was formalised further in 1952, when the Common Travel Area was created, enabling Irish and UK citizens to be treated almost identically within both states. It was partly due to the existence of that Common Travel Area that both states remained outside the Schengen zone, which includes all other EU members as well as some non-EU states such as Norway, Iceland, Switzerland and Liechtenstein.

EU decision

Pressure to seal the Border could come from any one of three places. The Government could insist on Border controls as a way of protecting the EU’s external borders. If Ireland joined Schengen after a Brexit, it would be for the EU to decide how UK nationals could gain access to Ireland and therefore how the Border would operate.

Alternatively, given that migration has been an important factor driving the Leave campaign, the British government itself could come under pressure to impose Border checks to prevent Ireland becoming an access point for undocumented migrants.

Privately, neither Dublin nor London wants to see Border controls introduced. Both sides believe the adverse impact on trade and on the peace process would be too great.

The Northern political parties are also firmly against the idea. “I’m pretty sure there would be a pragmatic approach by the British and Irish governments to finding some kind of way of dealing with potential problems on the Border without going down the road of thinking about a hard Border,” according to an Irish official.

That’s largely the view in Aughnacloy, but the uncertainty casts a pall over business in the village. For Gary McKenna, who owns the Expressway grocer’s shop on Moore Street, the return of Border controls would be “a disaster” for retailers at a time when the town’s fortunes have begun to lift (eight new businesses have opened in the past 18 months)

“It would leave this town desolate,” he says. “Business is hard at the minute with the currency exchange rate . . . never mind further complications.”

Troubled times

McKenna opened his shop in 1985, when most of his friends were emigrating to the United States. He struggled through the late 1980s and early 1990s, then saw business transformed "overnight" after the 1994 IRA ceasefire.

“The 1980s were a very difficult time to trade. You had a mixture: the currency, the Troubles, the customs. It was very difficult,” he says.

Losing a significant share of the through-traffic on which Aughnacloy relies would leave local retailers reeling. “There’s a bit of a feel-good after the recession now. We’re getting out of that darkness again,” he says. “But like any business, you need footfall.”

Few doubt the damaging economic impact of a restricted Border, but local concerns go beyond commerce. “The biggest fear would be the possibility of trouble starting again,” says Ciara King. “From my experience listening to the people I interviewed, I’m quite sure it would be something that would be playing on people’s minds.”

Opinion polls over the past six months have shown a solid majority of voters in Northern Ireland would prefer to stay in the EU, though the gap has been narrowing.

A poll for the Sun, conducted among 2,886 respondents online in February by the pollster LucidTalk, showed 55 per cent would vote to remain in the EU, 29 per cent would opt to leave and more than 14 per cent were undecided. Support for staying in was much stronger among nationalists, 74 per cent of whom said they would vote to keep the UK in the EU. On the unionist side, 64 per cent said they would vote to leave.

Little choice

Whatever strength of feeling exists, however, is tempered by the knowledge that if the vote in Britain is decisive, the North’s voters could have relatively little say in the matter.

“There’s a big feeling amongst people here that it doesn’t matter what we think, because we’re going to be lost in the population of the UK anyway,” says Stephen Salley, who says he will vote to stay in the EU. “People are saying, ‘what’s the point in thinking about this?’, because at the end of the day, there are 63 million people voting and we’re 1½ [million] so how much influence are we going to have really?”