George Mitchell has recalled the dramatic moment more times than he can count.

Fifteen years ago next month, as leaders across the once-perilous political spectrum of Northern Ireland basked in the glow of the Good Friday Agreement, the former senator from Maine who brokered the pact made them a promise.

Recalling that his son, Andrew, had been born just six months earlier, Mitchell said he would one day return with his boy to watch the Northern Ireland Assembly go about the business of governing.

“There will be no talk of war, because the war will be long over,” Mitchell predicted. “And no talk of peace, because peace will be taken for granted.”

Fast-forward to “George Mitchell: My Journey’s End,” an hourlong BBC documentary that makes its U.S. debut April 12 at the Maine Irish Heritage Center in Portland.

There, midway through the film, sits Mitchell in the all-but-empty visitors gallery as a government minister drones on to the Northern Ireland Assembly about a conference he just attended in Brussels. And there right next to Mitchell sits Andrew, now 15.

“I love Northern Ireland. And I love Andrew,” said Mitchell, borrowing a line from the movie, in a telephone interview last week. “And I thought it would be good for the two of them to become acquainted.”

It all started in late 2011 when Trevor Birney, director of the BBC in Northern Ireland, called Mitchell with a tantalizing question: That promise Mitchell made about his son all those years ago had he ever followed through with it?

No, Mitchell confessed, he hadn’t.

Would he like to – with a film crew from the BBC tagging along?

Mitchell talked it over with his wife, Heather. Then he broached it with Andrew, who was not initially thrilled with the idea.

“Unlike his father, he doesn’t care for the spotlight,” chuckled Mitchell. “But nice guy that he is, he agreed to do it.”

So in March of 2012, the family, which also includes 12-year-old Claire, headed across the Atlantic to witness firsthand the fruits of what Mitchell now calls “the most demanding role of my life.”

The documentary’s theme centers on one of Mitchell’s signature moments during negotiations that dragged on, when they progressed at all, for two long years. So slow was the progress that when he returned home for the birth of his son on Oct. 16, 1997, Mitchell thought seriously about giving up on the talks altogether.

Just hours after Andrew’s arrival, still at the hospital in New York City, Mitchell shared those misgivings with his wife.

“She urged me to go back,” he recalled.

Mitchell, using a pay phone at the hospital, then called his assistant in Belfast. His simple question: How many children were born today, the same day as my son’s birth, in Northern Ireland?

The answer was 61.

“Those children are entitled to the same chance in life that I want for my son,” Mitchell told the hushed negotiators upon his return to Belfast a few days later. “Peace, political stability and reconciliation are not too much to ask for. They are the minimum that a decent civilized society provides.”

Documentary producer Michael Fanning tracked down three of those children. And over three days, the Mitchells visited them and their families – the Robinsons in County Fermanagh, the Bests in County Down and the Stevensons in County Derry.

In each vignette, the grown-ups chat about what has changed – and what hasn’t – since The Troubles left Northern Ireland’s Catholics and Protestants alike living in constant fear of assassinations, bombings and other tit-for-tat acts of terror.

Yes, they tell him, the violence is all but gone. But the neighborhood-by-neighborhood segregation, rooted in personal loss and still-smoldering anger, remains.

Nicola Stevenson’s husband, Ian, is a police officer. She explains how even now the family’s vehicles must be checked for bombs before anyone heads out in the morning.

“Peace for us isn’t very peaceful,” Nicola Stevenson tells an empathetic Mitchell. “Because you’ve got that fear always hanging over you.”

Or, as young Lucy Stevenson confides to Andrew while giving him an archery lesson at a nearby community center, “Sometimes, when there’s a policeman been shot, you sort of think, ‘Oh my goodness, that could have been my dad.’ “

Yet despite the lingering fear (a policeman in County Armagh was shot and killed by an IRA splinter group as recently as 2009), it is the children – all precisely the same age – who weave a thread of hope into this narrative.

“I’ve heard Mom and Dad talk about problems and troubles that was,” Conor Robinson tells a curious Andrew during their tour of the family’s idyllic farm. “But I’ve never experienced any troubles or nothing like that.”

Nor has Alex Best. He takes Andrew to his school outside Belfast, where they soon find themselves staring up at faraway Stormont – the site of the peace talks and now the seat of Northern Ireland’s government.

“He could have stayed home and helped you,” says Alex of Andrew’s father. “But he decided to come over here and help me.”

“Yes, exactly,” replies Andrew with a smile.

“Well, tell him thanks,” grins Alex.

Then there’s Claire Gallagher. She was 15 the day, four months after the Good Friday Agreement was signed, that the Rear Irish Republican Army killed 29 people and wounded another 220 with a massive car bomb in the town of Omagh.

Gallagher, who met Mitchell when he and President Bill Clinton visited the town two weeks later, lost her eyesight in the blast. But she never lost hope that the fragile peace agreement, too, would survive.

“I suppose I just never considered that someone like the senator would remember me – and would continue to remember me,” Gallagher, now married with children of her own, tells the BBC crew as the Mitchells arrive for a visit.

Remember her? Mitchell named his daughter after her.

“George Mitchell: My Journey’s End” will be shown at the Maine Irish Heritage Center on Gray Street in Portland at 7 p.m. April 12 and again at 2 p.m. April 14.

It is, explained Mary McAleney, a former member of Mitchell’s U.S. Senate staff and now chairwoman of the center’s board of directors, a chance “to celebrate and recognize what the senator did, what a man from Maine did and what a person who’s Irish did.”

And how Mitchell, himself the grandson of Irish immigrants, kept that promise he made way back on April 10, 1998.

“Because I had children late in life, I’m not going to see my kids grow into full adulthood,” said Mitchell, who will turn 80 in August. “I wanted them to get a sense of what had been a very important part of my life in Northern Ireland.”

During their visit to Stormont, as they sat alone (without microphones) in that visitors gallery listening to the minister’s endless briefing to the Assembly, Andrew finally turned to his father and said, “Dad, this is really boring.”

“Well,” Mitchell told his son with a smile, “that’s the point.”

Mission accomplished?

” ‘This is really boring!’ ” echoed Mitchell with a chuckle last week. “It was a perfectly fitting ending.”

Bill Nemitz can be contacted at 791-6323 or at:

bnemitz@mainetoday.com