Rock lore tells of a younger, angrier Nick Cave, the sort who might swipe a scythe at an NME journalist. As the frontman to waspy noiseniks The Birthday Party (from 1978 to 1983), Cave routinely attracted a mob of angry, screeching, pissing fans.

“First time we got pissed on was in Glasgow,” he recalls. “That was from the rafters. A particularly unpleasant way to get pissed on. One thing to have somebody piss on your leg. But on the top of your head is a whole different thing.”

Today, straight-backed on a gilt-edged chair, Cave can boast that his style and appearance has changed little since those pissy post-punk days or since his earlier Gothic ones with The Bad Seeds. But he is different, surely?

Tender massage

His wife Suzie massages his face tenderly. He takes slow bites from an apple. It seems he now lives quietly with his twin sons in Brighton by the sea. “I didn’t like the sea before,” Cave says. “I’m a river guy. My whole childhood was spent by rivers. Rivers have something that is mystical and free-flowing and forever in the present. They’re nonhistorical. There’s something idiotic about the sea. It just comes back and forth. It’s taken me quite a while of living in Brighton to adjust to that.”

He smiles. “All that idiotic lapping it does.”

Cave has said that he ceased to be human around the end of the 20th century, around the time he relocated to the English coast. “But I better not talk about that. I think that’s a lovely enigmatic statement that would only be diminished by anything I say.”

He pauses, then smiles again: “I don’t take as many drugs,” he offers, helpfully.

June 24th, 2013, Nick Cave's 20,000th day on earth, was the first day of recording The Bad Seeds' 15th studio album, Push the Sky Away, which would go on to win an Ivor Novello Award. It was also the temporal setting for 20,000 Days on Earth, a new documentary directed by the artists Iain Forsyth and Jane Pollard.

In keeping with its singular subject, the film rarely resembles a regular rockumentary. Instead, it pieces together glimpses of studio work and home life under Cave's narration, a stream of poetry weaving through candid recollections of growing up in rural Australia, garret life in Berlin and heroin days in London. Cameo appearances from former collaborators Kylie Minogue and Blixa Bargeld add further splashes of colour.

Cave describes his early years in Warracknabeal in northwest Victoria as an idyllic time of playing by train tracks and kissing girls. His father was a schoolteacher, his mother a librarian. “I had a good childhood,” he says. “I wasn’t beaten. I wasn’t sexually abused. I had a lot of freedom. I had loving parents.”

So where did all the darkness that hangs around his writing and music come from? “Well, it’s a paradox. As long as I can remember I’ve had a pre-disposition toward violent thought. As a schoolkid I remember a visceral thrill from writing about violence. But we’d be wasting our time if we tried to figure out why I write the way I do. Maybe it’s just DNA.”

Father’s death

Maybe. Disappointingly, he can’t point to a single transported convict among his ancestors: “Unfortunately not. My grandfather was German and my grandmother was English. All Australians want a convict past these days. But I don’t have one.”

The one recognisable shadow across Cave’s younger life was the premature death of his father, a figure he discusses extensively in the new film.

Cave has frequently collaborated with women, among them Lydia Lunch, PJ Harvey and Neko Case. He honed his storytelling skills telling bedtime stories to his sister. I wonder about his female influences. I wonder about his mother. "My father was one for the grand gesture. But I'm far more like my mother, who is still around, who has a sort of slow steady movement that goes through her life. That flow has more of an influence over me."

Like a river? “Exactly,” he grins. “My mother is like a river. My father’s like the sea.”

Before moving to Brighton, Cave lived in Berlin, London and South America. He is, he notes, part of the colonial generation that "had to go to the UK in order to find out if your art was worth anything".

That’s difficult to picture. Cave’s prolific and often experimental output points to someone who isn’t afraid of failure, someone who is happy to work without a safety net. “Well, the creative process should be uncomfortable. It should be scary. I’m always looking for a sense of unease. Of dread. If you write another song and you think it’s good when all that’s happening is that you’re being reminded of things you’ve already done.

“That’s why I like eccentric people. And on some level, I like pretentious people. People who have inflated views of themselves. I admire people like that. It’s one of the aspects of Australia that I never liked. That sense of pushing people down if you stick your head up too high. Australians aren’t unique in this. The Irish have it too.”

All these years after leaving, is there any part of brain that still thinks Australian? “My sense of humour. That self-deprecating humour. A need to deflate your own pretensions. But like I said, I also like pretensions.”

Cave smiles again: “Another paradox.”