Former Northern Ireland first minister says any special deal to keep region in Europe would destroy key tenet of Good Friday agreement

David Trimble, whose support was critical in creating the Good Friday agreement, has warned that the Irish government risks provoking loyalist paramilitaries with its stance on the border after Brexit.

In a wide-ranging interview to mark the 20th anniversary of the agreement, Lord Trimble said any special deal to keep the region within Europe would destroy a key tenet of the agreement that there would no constitutional change without majority consent in Northern Ireland.

“What is happening now is that people are talking up the issue of Brexit and the border for the benefit of a different agenda from the agreement,” Trimble said. “The one thing that would provoke loyalist paramilitaries is the present Irish government saying silly things about the border and the constitutional issue. If it looks as though the constitutional arrangements of the agreement, based on the principle of consent, are going to be superseded by so-called ‘special EU status’ then that is going to weaken the union and undermine the very agreement that Dublin says it wants to uphold.”

Q&A What is the Good Friday agreement? Show Hide The Good Friday agreement, also known as the Belfast agreement, was signed on Good Friday 1998 and effectively brought an end to the Northern Ireland Troubles. The two key political tenets of the agreement were that Northern Ireland would remain part of the UK until a majority in the region voted to join the Irish Republic, the so-called principle of consent, and that any devolved government would comprise a cross-community partnership in which both unionists and nationalists shared power. In order to emphasise the equal influence both communities would have the offices of the two key politicians elected to a new Assembly, the first and deputy first ministers, would have equal status.

The agreement also led to a de facto amnesty for republican and loyalist paramilitary prisoners. It resulted in the early release of about 500 inmates including some who had committed mass murder. In May 1998 the agreement was ratified in a referendum on both sides of the Irish border. Just over 71% backed the deal in Northern Ireland, with 94% of voters supporting the agreement in the Irish Republic.

It also created institutions to promote north-south co-operation on economic and social matters throughout Ireland. The agreement is held up as a template for resolving political, especially rival ethnic, conflicts in other parts of the world.

Trimble was the Ulster Unionist leader at the time of the Good Friday negotiations and his backing for the agreement was crucial to its success. He was later awarded the Nobel prize for his efforts to secure peace in the region and was awarded a life peerage in 2006.

But the former first minister of Norther Ireland said he believed loyalist paramilitaries could reactivate if the principle of consent enshrined in the agreement was put in danger by any post-Brexit deal demanded by the Irish government and nationalist parties.

“I believe that some senior Irish government officials go around Brussels talking about the ‘Hong Kong model’ – the one country, two systems idea,” Trimble said. “That is a precedent they talk about where sovereignty has been transferred from Britain to China. Anything that looks remotely like this or is building on that foundation would be extremely dangerous. Although I think that under this Conservative government I cannot see that prevailing.”

Trimble also claimed another threat to the union between Northern Ireland and the rest of the UK was the Democratic Unionists alienating pro-union Catholics and the “moderate middle classes” in general over issues such as the party’s opposition to gay marriage equality.

And the DUP made a mistake by asking for £1 bn as the price for keeping the Conservatives in power, Trimble said.

“When the DUP asked for that money it was always going to infuriate Scotland, Wales, many of the English regions. That is how you lose friends in Britain as well as the votes especially of the moderate middle classes in Northern Ireland.”

The Tory peer was equally downbeat about the possibility of a Jeremy Corbyn government, which he thinks may agree to Northern Ireland being given special status inside the EU after Brexit, which in turn would decouple the region from the UK.

“His right-hand man [John McDonnell] who in government might get a rush of blood to the head and go to his old mates like Gerry Adams and give him what they want. If he and Corbyn were the two leading figures in a Labour government and created ‘special status’ after Brexit that would be very dangerous.”

While having “no real regrets” in signing the agreement even after it split his party, Trimble said he wished he had kept closer to Tony Blair when he was prime minister. By the time he lost his Upper Bann parliamentary seat in the 2005 general election, Blair’s government was already pursuing a strategy of “wooing the extremes”, according to Trimble, by seeking support for a second agreement, between Sinn Féin and the DUP.

“I genuinely believe that Blair was the last person to back a strategy which effectively saw the two centre parties, the UUP and the SDLP, abandoned. In fact I know now it was a very senior civil servant in the Northern Ireland Office who agreed to the strategy, proposed by the Department of Foreign Affairs in Dublin..”

Trimble said Blair’s letter of assurance over IRA disarmament that he gave Trimble’s negotiating team less than 24 hours before Good Friday 1998 was “absolutely critical and vital” in securing UUP support for the agreement. Under the rules of the talk the agreement would not have come into existence unless it acquired the backing of both major unionist and nationalist parties around the negotiating table.

One of Trimble’s most vocal internal critics in the UUP after he backed the Good Friday agreement was Arlene Foster, the leader of the DUP. While he said he sympathises with the problems Foster has to deal with in the absence of a power-sharing government in Belfast, he laughed and added: “Do you know that in all the times when I was UUP leader and she used to be in the party before defecting to the DUP, Arlene never spoke to me once.

“Other internal critics like Jeffrey Donaldson [once an Ulster Unionist now the DUP MP for Lagan Valley] always went out of their way to speak to me even when the UUP was a divided house over the agreement. Jeffrey was always civil with me despite our differences but I cannot recall one occasion where Arlene said anything to me at all.”