Good Friday Agreement structures can only be reformed if all sides back it, Tony Blair warns

The ex-Labour leader, who played a pivotal role in negotiating the historic deal in 1998, said there was a case for reforming the devolved powersharing structures at Stormont, given the regularity of governance collapses in the region in the 25 years since.

The arrangements incorporate a system based on mutual veto powers, enabling blocs of unionist and nationalist MLAs to stop moves that otherwise command majority support and, in extreme circumstances, pull down the institutions and prevent them operating.

The DUP is currently exercising its veto to blockade Stormont in protest at post-Brexit trading arrangements.

In 2017, Sinn Fein collapsed the ministerial executive amid a furore about a botched green energy scheme.

The current UK Government has faced calls from some of the DUP's main rivals, particularly the cross community Alliance Party, to change the rules to allow the majority of MLAs to get back to work.

However, in an interview with the PA news agency to mark the 25th anniversary of the Good Friday deal, Sir Tony cautioned against any move to alter the veto system to circumvent the DUP stance and reinstate powersharing, saying reform could only come if it was supported across the different traditions in Northern Ireland.

"People often ask me whether there's a case for reviewing the Good Friday Agreement, the institutions, the way one party essentially can veto the process, and I always say to people that of course there is a case for reviewing it and, in time, maybe that review process will yield a change," he said.

"But I don't think you can yield a change that's going to work unless it brings the communities together.

"And one thing I've learned about Northern Ireland is that there's a difference between the ideal answer and the realistic answer.

"The ideal answer may be that you change the whole system, for example, by the way you choose ministers or have the executive up and running.

"But the realistic truth is if you were to act, for example, in direct contravention of a large part of unionist opinion, it wouldn't work, it just wouldn't work.

"So, yes, in an ideal world the politics of Northern Ireland would be historically different, but they're not, you're in the real world and in the real world, of course, I think we should keep the agreement under review the whole time.

"But I don't think it's possible to change it unless you get the most important elements in Northern Ireland politics in agreement."

Sir Tony said change could not just be "top down" and needed to involve an element of "bottom up" endorsement by grass roots communities.

"The basic agreement in its essence, which is fair treatment for all parts of the community in return for the principle of consent (on Northern Ireland's constitutional status), I think that that will always remain.

"But how you adjust the way you manage institutions, the different strands, obviously that can change, can be adjusted in time, but it will have to be by agreement," he said.

Reflecting on the Good Friday negotiations, Sir Tony said the leaders of 1998 offered a lesson to the current generation.

"It was agonising (the talks process), but it's an interesting reflection on politics that it works best when leaders are prepared to say even to their own supporters things that are uncomfortable," the former PM said.

"I think it's important when people remember figures like David Trimble (Ulster Unionist leader) and John Hume and Seamus Mallon (SDLP leadership) is to remember what it was that has made them stand out and why we rightly respect their contribution today, and that is because they tried to do what they thought was genuinely in the interests of Northern Ireland in the end.

"When people think of politics sometimes as a very brutal game, or a game that's all about egos and power and intrigue, they rose above it, they rose above all the petty things in politics and did something substantial and will be remembered for it, which is important because it's a lesson for today's generation of politicians."

He added: "I think these agreements can always be made.

"And of course, to a degree, they are dependent on context and time and timing. But I think they can always be made if there's leadership, if people are prepared to lead and the essence of leadership is being prepared to do difficult things."

While the accord largely ended the violence in Northern Ireland, Sir Tony acknowledged there is more work to do to secure true reconciliation in the region.

"One of things I learned about the peace process is you can create an agreement, and you can create a legal framework, and you can do the reforms and pass the laws, but that's not the same as two communities trusting each other," he said.

"And I think it just takes time, it takes quite a lot of time."

He added: "I think there's still a lot of reconciliation to happen.

"But at least if there's peace and, if we get back to some form of political stability, I think you've got the right circumstances for that reconciliation."

Sir Tony emphasised how important Northern Ireland was to his premiership.

"The first speech I made when I was prime minister was in Northern Ireland," he said.

"I was determined from the outset to give it a real go.

"I realised John Major had put a lot of effort in. I thought we could if we really worked at it, bring it to an agreement.

"We then negotiated.

"Obviously, I was personally doing the negotiation to get the Good Friday Agreement and then I spent the next nine years trying to make it come to fruition.

"And I probably went more times to Northern Ireland than probably the rest of my predecessors put together I should think, that's probably not inaccurate.

"So yes, of course it was a big part of what I did, but it could never be done without those other people, the leaders there in the community in Northern Ireland being prepared to lead."