For their film Life is a Very Strange Thing, Australian husband and wife filmmakers Les McLaren and Annie Stiven caught up with an old friend they hadn't seen in four decades.

When they met him in the mid-1970s in Papua New Guinea, Frenchman Frederic Duvelle was a troubled 17-year-old whose father Charles had brought him along when he was working as an ethnomusicologist to establish a music archive.

McLaren says he and his wife were there independently.  The PNG government had received a grant from the Whitlam government to set up a national museum, national art school and theatre company to help foster nationalism as the land with many languages moved towards independence and the couple were working with these agencies.

"His father had to go back to Radio France but Frederic stayed on five years to buils the archive," McLaren says.

McLaren says he himself went back on and off for 10 years, the longest single stay being for six years.

He says he and Duvelle barely stayed in contact with each other but he received updates through a common friend about what was happening in Frederic's life — marriage, daughters, a job in a recycling company that took him to several countries.

"It was getting on to 40 years before we met again," he says.

"We were in France — we had both come to work on another project — and the friend suggested we get in touch with Frederic.

"He was recently divorced, recently retired, his daughters had left him to go study, so he was left to his own devices with a small ancient dog."

They reconnected and discovered Duvelle was what the French call a personage, a personality — a worthy subject for filming.

"He's bigger than life, he fills the room," McLaren says.

"He's a great raconteur and very perceptive and engaged with things in many ways — all things I quite like."

McLaren says, "We thought it was going to be more a biography about a person."

That element still comes through: we meet Duvelle's elderly parents, his daughters — one of whom was frighteningly close to the terrorist attack in Paris on November 13, 2015 — and his niece, a feminist activist, and learn something of his own past and his family history, including his grandfather who was a colonial governor in Cambodia.

But McLaren says the film turned into something rather different: Duvelle became the conduit for a look at the state of France today.

"That came through more strongly than we would have suspected at the start," McLaren says, saying the film was made in the tradition of other observational and direct cinema documentaries. Periodically, from 2015 to 2017, Duvelle wore a radio mike and McLaren followed him around with a small camera, recording his comments, his interactions with people and the events that took place around them.

As the film shows, like many French people — and unlike many Australians, as a couple of those filmed are keen to point out — Duvelle is passionate about politics and serious discussions about issues and parties and candidates around election time often take place among family, friends and acquaintances — and even, sometimes, strangers.

The rise of populism in Europe in general and in France in particular is one subject the people filmed discuss. It's one of the things Duvalle notices that's different about the country now.

And sometimes the topics broached can reach into the past and the results can become quite acrimonious.

In one lucky accident, McLaren was filming in a shop where a heated argument broke out between two people over something that happened during the Algierianian independence movement. Such matters are still close to the surface in France.

McLaren says Duvelle is satisfied with the final film.

"He gave us carte blanche to film it. He was generous in every way."

The only subject they avoided treating in any detail was his ex-wife. The divorce was still too recent and too raw.

"We didn't go there. I've not met her."

While he's had his ups and downs, what most impresses McLaren about Duvelle is the zest for life he's always shown. He developed from the impressionable, trouble-prone teenager who was taken to Papua New Guinea by his father to the man who took on increasing responsibilities, both professional and personal, and made something of himself, while never losing his spirit. And the film he and his wife have made — part biography, part character study, part examination of the state of a nation — celebrates this.