In the city where the Troubles erupted in the 1960s, hardline Irish republicans opposed to the political settlement in the region are delighted about Britain’s exit from the European Union.

Brexit for them signals a chance to break up another union – the one linking the six counties of Northern Ireland with the rest of Britain.

As the political classes in both London and Dublin absorb the shock from Thursday’s EU vote, republican dissidents in Derry believe that in the long term Brexit will mean the breakup of Britain.

Barrister Plunkett Nugent, originally from Galbally/Cappagh in the east Tyrone republican heartland, welcomed the Brexit vote, stating that “Scotland will be gone and that can only be a good thing”.

A member of the 1916 Societies – an alliance of dissident republicans opposed to Sinn Féin’s political strategy – Nugent said: “Brexit has lifted a veil of deceit in relation to the border and the partition of Ireland. Thursday’s vote and the outcome means the border will be physically manifested again. It shows there still is a border, as well as the political reality of partition.”

Following the referendum, the deputy first minister of Northern Ireland, Sinn Féin’s Martin McGuinness, demanded a border poll on the future of the region in the UK. This was swiftly rejected both by Democratic Unionist first minister Arlene Foster and the Northern Ireland secretary, Theresa Villiers.

For republicans like Nugent, who is a former Sinn Féin member, that has proved where the real power lies. “The Brexit vote, against the wishes of the people of the north of Ireland, who voted to stay in the EU, and then Foster’s and Villiers’s dismissal of a border poll, shows that Sinn Fein’s strategy is in tatters,” he said.

“The Belfast Good Friday agreement contains legislation that restricts that poll to the north of Ireland and, besides, if a British secretary of state doesn’t like the outcome they can ignore it. Brexit exposes the inherent flaws in the agreement. England suits itself and the north of Ireland doesn’t count.”

Another dissident republican, who is close to the New IRA group, said that most hardliners welcomed the Brexit vote: “For the first time, anti-Good Friday agreement republicans are on the same side as the apolitical people in the street here in Derry – the men and women who are furious that while they voted to stay in the EU the English voters were the ones that counted.

“They are angry that they are no longer in Europe, and we can turn round now and say, ‘We told you so. In terms of what England wants, your concerns don’t really count.’ Our task is to use Brexit as an opportunity to build support.”

The 1916 Societies are campaigning for an island-wide referendum on Irish unity, but most people living in Derry have more pressing day-to-day concerns. Exiting the EU, and the potential economic cost of doing so, was troubling many in the city only 48 hours after the Brexit vote.

Walking across Derry’s Peace Bridge spanning the river Foyle, which was partly funded by the European Union, Andrea Russell said she was deeply worried about Brexit’s impact on a city with some of the most deprived electoral wards in the UK.

Crossing from the mainly unionist east bank to the nationalist-dominated west bank, Russell looked back at the striking bridge, which opened in 2011. “This bridge wouldn’t have been built without millions from Europe,” she said. “There are community centres, after-school clubs, youth clubs, football teams, Gaelic sides who have been funded by the EU through the years. I’m not confident we can get that same sort of support outside of the EU from the British government in London.”

The new, Derry-born leader of the Social Democratic and Labour party, Colum Eastwood, said he had noticed something interesting during the counting of votes on Thursday night and Friday morning.

“In nationalist wards like Creggan, surprisingly, there were Out votes tumbling out of the ballot boxes. These were not voters for the anti-EU DUP, as these are areas in the nationalist side of the city. It is clear some dissident republicans were voting Leave while others were encouraging no turnout. Brexit suits their agenda of destabilisation,” Eastwood said.

Unionist voters who backed Leave deny that Brexit will lead to Britain breaking up. Tony Crowe, a historian and member of the loyalist Apprentice Boys of Derry, described such fears as “mere hype”. He added: “I voted Leave not because I am one of them Ukip nutters who hates immigrants. I simply don’t like the lack of democracy in the EU. As for the UK, I think when the dust settles, the people of Scotland will take a cold hard look and realise they are still better off with the rest of us.”