Director Molly Reynolds was reflecting on the life of our greatest Indigenous actor, David Gulpilil, the subject of her new documentary film. My Name is Gulpilil world premiered in Adelaide in March.

Gulpilil's life was surreal. One moment in 1969, the 16-year-old was destined for the life of a traditional Indigenous man in East Arnhem Land.

Next moment, he was on the set of Nicolas Roeg's film Walkabout as the boy who tries to guide two white city children abandoned in the outback.

Then, he was on the plane to London to meet the Queen, and visit Cannes where Walkabout was screening in competition. How does any boy from the back of beyond get his head around that?

Now 68, Gulpilil's life hangs in the balance. He was diagnosed with widespread, stage-four lung cancer in 2017 and not expected to survive into the following year. Remarkably, he is still with us.

"He rallied for the premiere in Adelaide, but he is no longer hearty," Reynolds says in our interview.

Gulpilil must be very changed from the man who spent six weeks as a house guest of Reynolds and her partner, Rolf de Heer, while working on the voiceover for Ten Canoes.

Since Ten Canoes was released to critical and commercial acclaim in 2006, there have been ongoing collaborations between Reynolds, de Heer and the people of Ramingining, with projects such as Twelve Canoes and Another Country.

Work on My Name is Gulpilil began in 2017, with Peter Djigirr and Rolf de Heer as producers. "The Adelaide Film Festival was first in on funding this. A definitive work, Gulpilil's last work, a film that ought to be made," she says.

"We budgeted for 30 days but the shoot took 67. David was so keen and kept going, and going."

Gulpilil now lives with his carer, Mary Hood, in Murray Bridge, South Australia. "Gulpilil doesn't leave Mary's side now. The only other person he will be alone with, without Mary, is Rolf."

It seems a cruel irony that Gulpilil, a Mandipingu man of the Yolngu culture, is so far from country. "Yes, there have been many attempts to return him to his homeland, but it's his decision to stay where he is."

He used to share an apartment with his carer, a former nurse, in Darwin. "Mary decided to leave Darwin. She'd had enough of the tropics, and the humbug, and David said he was going with her, to which she said 'oh, okay'.

"She is a real character in the film. A hero of the story."

It's lovely to observe these elderly companions, David and Mary, together. They certainly often have a laugh together, even over the oxygen concentrator that helps Gulpilil stay alive.

For a film about a man with a terminal illness, it is heartening to be reminded of Gulpilil's legendary sense of humour, with clips of amusing scenes selected from his filmography like Crocodile Dundee, The Tracker and Ten Canoes.

There are also excerpts from his one-man stage show, including Gulpilil's hilarious recollections of his dinner with Queen and her family.

"He also has tremendous capacity for poetic expression," observes Reynolds. "During the 50 or more interviews we did, he might talk for an hour. Then come up with pure gold."

It's well known that Gulpilil learnt a lot through observation, including English as a teenager.

"He's quick-witted, and as an outsider looking in, he can see the foibles of white-fella culture, and works with that."

Many would agree that he is also one of the most charismatic actors on screen. How does he do it?

"He just looks at the lens and comes alive," she says.

Or, as he himself would say, he just stands there and lets the camera find him.

Gulpilil was sure to be comfortable in front of the camera, despite his illness and frailty, but Reynolds had to be clear about some uncomfortable truths from the start.

"I said that we had to talk about the good, the bad and the ugly," Reynolds says.

"No one is going to appreciate this story unless we deal with your addictions, your imprisonment, your living in the long grass. You can only restore your good name if you deal with it head on.

"In his culture, you don't talk about the shameful stuff. In our culture, we tend to find it very cathartic. I think David was well reconciled to it, though I had to work a little bit to get there."

My Name is Gulpilil is such a delicate and moving tribute to the great actor and dancer, but where are the interviews with the famous directors, the Peter Weirs, Baz Luhrmanns, or Phil Noyces? Even his very close collaborator, the filmmaker Rolf de Heer, who Gulpilil calls his brother, only gets a passing reference.

"It is his story, in his own words. It was only going to be David's voice."

Ultimately, David Gulpilil's legacy speaks for itself, as does his presence in some of the most important films featuring Indigenous Australia ever made.

"David has had roles in films like Rabbit Proof Fence, The Tracker and Charlie's Country. They have awakened public consciousness about the children removed from their families, the frontier wars, and the dispossession."

It is a magnificent legacy to leave us with.

Now Gulpilil spends his time painting. "He is highly accomplished. And it's about having culture. He was taught those things as a young boy and it's a big part of who he is."

Life is quieter now, as Gulpilil creates water goannas and other creatures of Arnhem Land. It is a return to country, after all.