Boris Johnson has hailed a “very moving” church service to mark 100 years since the formation of Northern Ireland.

The Prime Minister was among a host of political leaders, including Irish Foreign Affairs Minister Simon Coveney and Northern Ireland’s First Minister Paul Givan, who attended the event at St Patrick’s Cathedral in Armagh.

The cross-community service heard a message of reconciliation from church leaders.

Mr Johnson said of the service: “It has been very moving to be here today and see the way in which people from very different perspectives have come together to celebrate what is an incredible place, an incredible part of the country which has got an amazing future.

“That was the message I took from the service this morning.”

He added: “I am a passionate unionist and, of course, I believe the future is within the United Kingdom.”

The Queen had been scheduled to attend but the trip was cancelled following medical advice, while Irish President Michael D Higgins turned down the invitation to the event.

The leaders of four of the five largest political parties in Northern Ireland were also in attendance.

Sinn Fein snubbed the ecumenical service organised by the four main churches in protest at partition.

The party’s vice president Michelle O’Neill simply tweeted “make partition history” on the day of the event.

However, speaking after the service, SDLP leader Colum Eastwood said it was “very clearly no celebration of partition”.

“It was a reflection of the events that have happened over the past 100 years and it was, I think, a hopeful vision for the future, putting young people front and centre,” he said.

Mr Eastwood said he felt partition was “coming to an end”, and urged consideration to how a shared island can be created.

“If we want to create a shared island, we have to be prepared to share rooms with people who disagree with us,” he said.

“I don’t criticise anyone for not coming but I think they should look very carefully at what happened today, it was a reflection, it was a marking of an historical event.

“It was a hopeful service looking to the future.”

Mr Eastwood also defended the decision by Mr Higgins not to attend, saying he has “a different set of circumstances to weigh up”.

However, DUP leader Sir Jeffrey Donaldson urged the Irish President to watch the service.

“Perhaps the president will have the opportunity to actually see down and watch this service, and perhaps see what it was truly about,” he said.

“It’s not about politics, it’s not about one side gloating or in any way seeking to be overbearing on the other, but actually all of us coming together to reflect on the journey that we have been on, difficult, painful that it has been at times but also a journey in which I hope we have learned a lot of things.

“I hope we have learned lessons from today, that we will reflect upon in the future and when we’re given the opportunity to stand shoulder to shoulder to reflect, to speak of hope, that in the future we will do it together.”

Sir Jeffrey also claimed Sinn Fein said “misjudged” the moment in their refusal to attend the service.

“It remains a disappointment that the Deputy First Minister felt unable to attend such a service of Reflection and Hope marking Northern Ireland’s centenary, where the focus was on reconciliation. 

“I think Sinn Fein yet again misjudged the moment and I hope lessons can be learned from this,” he said.

Sir Jeffrey described the service as “very moving” and a “great representation of Northern Ireland – inclusive, forward-looking with a focus on hope, reflection and reconciliation”.

He said there are “painful memories… of dark and difficult years” for many, but he said it is “right that we come here and share those reflections including the pain, but also the joy of living in this place”.

Ulster Unionist leader Doug Beattie said he felt it had been a “wonderfully uplifting service”.

He described it as a service “looking at our future”, and “achieving a better society for our children”.

“Unfortunately not everybody could be there, and that’s always a shame, but that’s the task for the next number of years, to try and get people to feel comfortable all being together and understanding what our differences are from the past,” he said.

“I think in the weeks and months to come people will look back and think what was the controversy all about… because what I saw was a real mix of people who classed themselves as Irish or British and many from other corners of the world.

“I thought it was a fantastic service of celebration in the term of celebrating our differences.”

Alliance Party leader Naomi Long termed the service as a “moment of reflection”.

“I think it was a moment of reconciliation and an opportunity for us to come together and to look forward with hope to the future, to look at the kind of gracious acts that we need to do if we’re going to reconcile a broken and hurting community and a broken and hurting people on this island,” she said.

“Peace-building requires risks, reconciliation requires risks, the church leaders took risks, I commend them for that and I’m glad I was able to be part of it today.”