The cliche “bursts into the room” was coined for people like Alex Fegan. Formerly a solicitor, now a creator of cracking populist documentaries, the endlessly jolly Dubliner brims over with anecdotes and good cheer.

He is just the sort of person to whom you would feel happy telling stories. In 2013 he got publicans of all stripes – solid, wary, eccentric – to open up in The Irish Pub. Now he has drawn out 30 of the nation's centenarians for a film titled (rather deliciously) Older Than Ireland.

"When I was finishing The Irish Pub, somebody told me they were going to a 100-year-old's birthday party," he says. "I thought: what an amazing thing. And, as we are approaching the anniversary of 1916, I thought that could be an interesting angle to take. It was a way of looking at that history."

Fegan and his team placed advertisements throughout the country asking for volunteers. That plan delivered a few worthwhile interviewees, but what really kicked the project forward was his discovery of an accidental network connecting those born more than 100 years ago.

“You’d go and talk to somebody and they’d know somebody in the next parish who was also 100. That was very useful,” he says.

Older Than Ireland ends up as an extraordinarily comprehensive document. Fegan interviewed 30 of the 300 or so centenarians living in the State. The resulting sample crosses all social demographics. There are working-class Dubliners. There are well-off rural professionals. There are relatives of rebels and of Anglo-Irish administrators. As the film progresses we get eyewitness accounts of great events, but it is the personal rather than the public that dominates.

Relationships

“Yes, the political side is only so interesting,” he says. “Their relationships are more interesting than their impressions of World War Two or whatever. What’s really interesting from the perspective of somebody who’s 100 are the things that we all experience: first day at school, marriage, having children.”

All this is true. The recollections of late spouses are particularly moving. Musings on school life in the 1920s and 1930s are rarely nostalgic. For all that, certain common opinions do emerge about the early days of the new nation.

“You have to be aware of the context,” Fegan explains. “They were alive at the origin of the State. So you have to listen to their views. They didn’t have any bitterness towards the English, for instance. They tended to think the Civil War was as bad as the Black and Tans. We tried to get that across.”

There is an impressive degree of optimism in Older Than Ireland. Most of the interviewees are happy to acknowledge the ways in which life has improved over the past 100 years. Still, even those of you a fifth their age will have decided that some aspects of modern life are rubbish. I wonder what changes they regretted most.

“The way neighbours behave,” he says, with no hesitation. “They almost all complained that people don’t talk to each other any more. We cocoon ourselves within our houses. That is a real problem with us now.”

I would guess Alex suffers less from this problem than most people of his generation. A graduate in economics and business, he studied to be a solicitor at the Law Society in Blackhall Place and went on to work in litigation. (He claims the training hasn't yet been much use in his new profession, while acknowledging that he does know his way around a contract.) He'd always fancied himself as a film-maker and, while litigating by day, shot a low-budget thriller called Man Made Men at night.

He eventually took the jump after fielding a call from a man who had ended up on the wrong end of a court case. “He phoned up and said, basically, that he wanted to do himself in,” he says. “I thought: this just isn’t funny. He might just be saying that. But it’s not for me to judge.”

Craftiness

The Irish Pub proved to be a great popular success. Clearly a man of no little craftiness, Alex distributed the picture in the US himself and somehow kept his shirt intact.

Older Than Ireland seems likely to have similar success. But does it answer the big questions? What is the secret to a long life?

“I wanted to get to what the secret was,” he says, laughing. “The first few I interviewed were very positive. I though that must be it. Then I met some who just didn’t want to live any more. So it wasn’t that. The first few were thin and lithe. Then I met some who hadn’t taken exercise for years. It’s genetics. It’s good luck.”

So what’s the answer then?

“There is no secret. That’s the secret.”

Older Than Ireland is out next week