Bertie Ahern asks the DUP "to stay the road with us".

The party is currently boycotting Stormont in protest against the Northern Ireland Protocol.

He says: "The people of Northern Ireland need them, the people on this island need them".

He adds that there are too many big things to be dealing with rather than arguing about what he calls a small detail.

Bill Clinton spoke about the importance of his personal relationship with the prime ministers of the UK and Ireland at the time of the Good Friday Agreement.

He recalled that Sir Tony Blair came to power on platform of policies that was "basically consistent with what I believed".

Then Clinton singled out Bertie Ahern for a backhanded compliment that made the audience laugh.

"Bertie had the kind of BS that I always wished I had. I wanna be Bertie when I grow up," he jokes.

"So we all got along and that's a big deal if you trust somebody, because if you make enough decisions under this kind of pressure, with all these changing circumstances, some of your decisions will be wrong or will be questioned or will not be good for one of your partners on any given day."

Clinton adds that the the trust they enjoyed helped through those inevitable difficulties.

Hillary Clinton jokes that this afternoon's panellists are a little nervous about appearing with her, especially her husband, Bill.

Blair recounts the final week of the talks when he and Ahern went to Belfast, even though the taoiseach's mother had just died.

"He took lots of abuse during the course of this process - people would come and be really rude to him," Blair says of Ahern.

"I got offended on his behalf, but he was never really offended."

Blair says the agreement would never have happened without that quality.

Bill Clinton also recalls his controversial decision to grant a US visa to Sinn Féin leader Gerry Adams in 1994, despite continuing IRA violence in Northern Ireland.

The former US president says he agreed to grant the visa provided there would be no IRA fundraising events attached to the trip.

"At the time it was crazy, they thought. I thought it made all the sense in the world, because what we were doing is not working and it seemed to me, just from the talk, that the public was maybe way ahead of the politicians in their desire to have some sort of resolution to this," Clinton says.

"So I gave Gerry the visa and he kept his word as he always did when dealing with me, and the rest is history."

Ahern is asked to reflect on the final week of negotiations.

The former taoiseach says "the issues were huge" and that dealing with the constitutional issues on both sides was a massive undertaking.

He praises the calls Tony Blair made saying "they were big calls and you did a good job on them."

Image source, Reuters

Blair says the negotiations were a rollercoaster, and the world's media camped outside Castle Buildings where negotiations were taking place added to the pressure the negotiators felt.

"As we carried on through the days and nights, there came a strange collective spirit of: 'Well we can't go out there and say it didn't work.'

Castle Buildings itself comes in for criticism both for its architecture and facilities.

Blair adds that Clinton was always on the end of phone, regardless of the time difference.

Earlier, George Mitchell watched on as a bust was unveiled in his honour outside Queen's university.

Bertie Ahern tells the audience that the negotiators got a few lucky breaks throughout the talks but that the process was as inclusive as he and Blair could make it given the circumstances.

He says the great thing about the talks was that "everybody knew they had to make tough decisions and the reality was that everybody did".

He also pays tribute to the late David Trimble, saying the Ulster Unionist leader at the time took big risks.

Ahern adds that the talks started badly after the Democratic Unionist Party walked out after Sinn Féin was included, but that the leadership of Trimble and other unionist politicians helped move things forward.

"When we began this, the first thing we did is...we agreed to talk to everybody," Tony Blair says.

"We had difficult jobs, but the people with the really difficult jobs were the politiicians of Northern Ireland."

Blair says after his first meeting with Sinn Féin he went to a shopping centre where he was met with people wearing washing up gloves, protesting that he had shaken hands with Gerry Adams.

He says his thinking was:"We know we disagree about the past, let's see if we can agree about the future

"I don't think anything would have happened if we hadn't sat down and talked to everybody."

Explaining the risks of appointing a special US envoy to Northern Ireland in the early 1990s, Bill Clinton says Irish-American advisers warned him of the political price he could pay.

"They told me: 'You have no idea how hard it is going to be for you to keep this commitment. People will think you're insane'," Clinton recalls.

"The State Department had operated for decades under a theory that our relationship with the UK was so important we couldn't mess it up."

"Even President Kennedy in his heralded visit to Ireland, did not go to the north and did not talk about it.

"You know, it was one of those things that wasn't done."

Bill Clinton tells the audience the people involved in the Good Friday Agreement had to take risks at the time, because they had to "figure out how you're going to do it and survive".

"All this stuff seems so straightforward today and easy, and it wasn't," Clinton says.

He recounts how he started to get interested in Irish politics when he was a student at Oxford University in the late 1960s, just as the violence of the Troubles was beginning.

He adds that people in the Irish community urged him to appoint a special envoy to Northern Ireland when he was running for the Democratic Party's presidential nomination.

Clinton says he resolved to do so, even though such a move was viewed as "heresy" at the time.

Image source, PA

Ahern recalls how one of the first things Blair did after becoming UK prime minister was to come to the Balmoral show in Northern Ireland, in his words this showed how he was going to give things a "good crack".

He references his working relationship with Bill Clinton by saying: "You were there all the time for us."

Ahern says that all the way from the summer of 1997 - when he became taoiseach - he was in 10 Downing Street almost every week.

"I think I hold the record for an Irish taoisech for that," he adds.

Image source, Reuters

Blair, who became UK prime minister in 1997, says his Conservative predecessor Sir John Major had already started the process.

He recalls how John Hume, who was a Westminster MP at the time, cornered him in the corridors of the Houses of Parliament telling him peace was possible.

And he speaks about his relationshop with Ahern and says there was a common thought of: "Let's give this a go."

"It was worth giving it our best shot."

The final event of the day is about to start, featuring three former national leaders.

Former US President Bill Clinton, former Prime Minister Sir Tony Blair and former Taoiseach (Irish Prime Minister) Bertie Ahern are on a panel chaired by Hillary Clinton.

The three men were heavily involved in negotiation the agreement in 1998.

Former Progressive Unionist Party leader Dawn Purvis says that the ceasefires of the mid-1990s by paramilitary organisations were crucial for allowing peace to develop.

She says it was important that people in communities beset by violence were able to live their lives without the sound of gunfire.

Purvis also pays tribute to her party's former leader the late David Ervine.

She says Ervine, who died in 2007, would remain dismayed that working class communities in Northern Ireland were still struggling.

She adds that smaller political parties need a voice in the assembly, and says the cut in its members from 108 to 90 should be reversed.

Ian Paisley enjoys some wordplay with the chairwoman of the panel - Nancy Soderberg - by calling her Nancy Soda Bread.

The Democratic Unionist Party (DUP) MP says his piece of magic for the day was the speech of Senator George Mitchell, which he described as a “masterclass in how to lead, how to construct, how to understand people.”

The DUP campaigned against the Good Friday Agreement in 1998.

Paisley argues that his party used its position to improve the power-sharing arrangements, which eventually led to his father governing with Sinn Feín's Martin McGuinness.

“I think that thing that marked it out was we had big beasts taking big, courageous decisions,” he said.

“Whether you were on the ‘no’ side – and people dismiss people who were on the ‘no’ side and said it wasn’t a courageous thing to do.

"It was as equally courageous to take that point of view, to have the alternative point of view."

Image source, Reuters

Lord Alderdice says in the 1990s there was a "zeitgeist" in which leaders who resolved conflict were praised.

Today, he says, leaders want to "conduct conflict rather than resolve it".

He says if there is one thing he could do differently, it would be on the implementation of the agreement.

He is asked what can be done to get Stormont up and running again and argues that Northern Ireland needs a different system of government.

Alderdice says the system should move away from the position of parallel consent and towards a "qualified majority" system.

Chairwoman Nancy Soderberg asks the panel what they would have done differently surrounding the negotiations.

Gary McMichael says he would not have wasted the year before the agreement "talking about nonsense" and kicking things down the road.

He says he thinks that would have helped build relationships and "nail things down" rather than leaving things unresolved which remain issues today.

Image source, Reuters

Earlier today we heard from former US Senator George Mitchell, who chaired the talks which led to the Good Friday Agreement.

This afternoon a bust was unveiled to him at Queen's University, where he served as chancellor from 1999-2009.

The former US special envoy to Northern Ireland watched on, along with Bill and Hillary Clinton and Sir Tony Blair.