You’re on a two-day visit to Britain to speak to MPs and the People’s Assembly. What’s the objective of these meetings?

I was very honoured to be invited to speak at the huge rally held in London with up to 250,000 people and to continue working with those people who are anti-austerity.

They are making what I consider to be very powerful arguments against the present economic strategies of this government, which are impacting so detrimentally on some of the most marginalised and vulnerable people in society, including people in employment threatened with further attacks in the budget on welfare and the working poor. 

In your meeting with MPs you talked about the impact of welfare cuts to the north of Ireland. There’s a £600 million black whole in your budget. Does that have the potential to damage the peace process?

I believe the peace process is very strong. I’m a passionate believer in the peace process. I’m not saying all this will bring the peace process down. Some people misinterpret what I say sometimes. What I’m saying is that the greatest threat to the institutions come not from dissident republicans or extreme loyalists who want to plunge us back into the past. The greatest threat to these institutions now, after 20 years, comes from the economic strategies being persued by this British government, which doesn’t take account that in the north of Ireland, we are a society still emerging from conflict. And we are a special case when you consider the terrible problems you have to deal with being a society emerging from conflict. The austerity agenda pursued by this British government doesn’t mix with that. So we have a situation where vulnerable people, many of whom have had serious mental problems as a result of the conflict, are now on the front line of attack by the Tory administration. 

You recently supported an interim budget for the next year that does not include welfare cuts. It’s been described as a “fantasy budget.” Where does that leave the north of Ireland?

I wouldn’t use that language. I think what that budget does is give space for real negotiation around the very serious issues around our executive’s ability to deliver for citizens and continue to move the peace process forward.

It is reality that there are still some people out there in the north who are hostile to the institutions, hostile to our involvement in the institutions. Who would, if they had the ability — and I don’t think they have the ability — drag us back to the past. Given the space that’s been provided now in the passing of the budget, there has to be a renewed effort to find a way forward on these very difficult issues. 

In the first five years of the Tory administration in the north of Ireland, they withdrew £1.5 billion out of a block grant. When these institutions were first established under the leadership of the DUP — namely Ian Paisley — myself and Gerry Adams, all of us went to Downing Street and met with Tony Blair and Gordon Brown. We negotiated a peace dividend to take us through to 2017-18. This British government, this Tory administration, has reneged on that agreement by withdrawing £1.5bn out of our budget, which has placed massive pressures on our ability to deliver public services. 

You’ve been branded “irresponsible” by ministers for refusing to support a budget in the north of Ireland that includes cuts. What’s your response?

There’s a headline in today’s Belfast Telegraph accusing politicians in the north of being as bad as the Greeks. I think in saying that the paper bestows a great honour on us. 

So you’re happy to be branded the Syriza of Ireland?

We’re happy to be fighting austerity alongside all those in different parts of Europe who are very concerned about how austerity is affecting society. Absolutely. 

Given your difficulties with this government, how disappointed were you that Labour lost the election, and how will the outcome determine the next five years for the north of Ireland?

My assessment is that Labour has a far better understanding and a greater empathy with the situation in the north, given that they were at the heart of the Good Friday negotiations and played such a powerful role in it. 

I know there’s a lot of criticism of Tony Blair in relation to the invasion of Iraq and Afghanistan. I do have to say he was the first British prime minister to make a very valuable and real contribution to peace in Ireland, the ending of discrimination and domination and institutions based on equality and parity of esteem. 

Did you have a good working relationship with Ed Miliband and the Labour front bench before the election?

I met Ed prior to the elections on a number of occasions. Obviously the election is over, the Labour Party lost. My own preference was to work with a Labour government, yes. But you have to play the hand you’re dealt with and the Tories are in power. I am part of a government in northern Ireland so I have to work with the Tories. But I also have to be true to myself as someone who is anti-austerity, is for the working class.

As Nelson Mandela said: “The measure of any government is not how they treat the most powerful in society but how they treat the weakest.” I’ve made it clear in interviews and speeches in recent times: I’m not going to have as my legacy that I was the person that was effectively the administrator of Tory cuts in the north of Ireland. 

You’re at the end of a two-day visit to Westminster. As a nationalist, do you begrudge the fact you have to come here?

I’ve been travelling to London extensively since the ceasefire and I think Londoners are the fairest people you could ever hope to meet. I’ve never had a hostile word said against me. People come up to me, they obviously see me on television, and they say: “Great to see you here. You’re doing great work.”That’s the most common remark that I get. All good. 

And what about Westminster itself?

We come here, we have MPs here, we have offices here. We meet with people from all different parties. I think everyone in all the parties appreciates the contribution we’ve made to peace. They know it’s historic. They know it wasn’t achieved easily. So I suppose there’s, maybe from a lot of people, a grudging respect for what we’ve done — if not total agreement on our attempts to bring about our primary political objective, which is a free and independent Ireland. 

You had led the polls in the south of Ireland until a recent slump. Are you concerned as you approach the 2016 Irish general election?

I’m not concerned about that at all. We’re going to have dramatic results in the next elections in the south.  If Sinn Fein don’t reach enough seats to get into government, Fianna Fail and Fianna Gael have a big decision to make about whether they’re going to go into coalition together. 

You don’t think the parallels being drawn between Sinn Fein and Syriza and Ireland and Greece have changed people’s perceptions for the worse?

No, I think our anti-austerity message has struck a chord with people all over the island of Ireland. At the minute, there’s a big debate about cuts to lone parents. We’re at the forefront of these arguments defending the most vulnerable people in society and we’re very proud to do that. 

I’ve had people say to me: “Why is Sinn Fein adopting such a strong line on protecting people’s welfare? They’re the people least likely to vote.”You even get some Unionist politicians saying that. This isn’t about votes. If it was about votes we would do what they did and be as opportunistic as they were. Whether they vote for us or not. It’s the families, it’s the children. And under no circumstances am I going to contribute to economic processes that see them end up in poverty.