Offbeat UK filmmaker Louis Theroux is hoping to use an upcoming tour to develop a long-held ambition to make a documentary about the Australian outback.

Theroux, known for his exploration of American subcultures and intriguing beliefs, behaviours, and institutions, will come to Australia for the first time to give live audiences a behind-the-scenes look at some of his films and documentaries.

He has captured the stories of the officers and inmates at San Quentin prison, and the extreme believers of the Westboro Baptist Church who picket American soldier's funerals over concerns the US military does not make an explicit stand against homosexuality.

Theroux also embedded with male porn performers of the San Fernando Valley, as well as a Nevada brothel, and the medical regime in one of America's leading centres of mental health for kids.

But he will also be using his upcoming tour, which launches in Perth, to explore Australian subcultures, and hopes to at some point document the outback.

"I've always been interested in the landscape of Australia," he said.

"The idea of the outback is hugely appealing.

"I've got a romantic association both with the American West and the Australian interior which seems to strike [an] emotional tone of austerity and size and remoteness, people carving out their destinies in this vast wilderness.

"I don't know exactly what the story is but I've loved the idea of being in that frontier ... the town at the end of line, this one-horse town with lives that combine dignity and a sense of desperation."

Theroux said he had been considering the Australian documentary for a number of years, but said the distance from the UK had been prohibitive, until now.

"This trip could be a prolonged reccie [reconnaissance] for me, this two-week tour I will keep my ear to the ground," he said.

'Non-threatening' demeanour gains Theroux access

Theroux puts part of his success in gaining access to communities and subjects with extreme belief systems in the US down to his "non-threatening" British demeanour.

"Americans in general are I think a little more publicity-friendly than British and Australians," he said.

But he added sometimes broadcast compromises were made to get an interviewee to agree to speak on camera.

"Very occasionally on very sensitive stories we've agreed to not to show them in America, which has meant that the most extreme stories in terms of the taboo that they involved, stories about sex offenders and paedophiles, as a production, we have agreed to embargo," he said.

Theroux said despite his best attempts, not all documentary ideas made it to air, including a recent story on radical Islamist believers.

"The guys that support the so-called Islamic State, and who are more or less in favour of beheadings, or if they don't say they are, they sort of are sympathetic, it was very hard to build trust," he said.

"We got a little bit of headway but not enough to get to the end of line.

"It's not one I've given up hope of making but it's not been easy."

'Dignity and stoicism people show in extremism'

Having spent a considerable amount of time in the US, Theroux described the current presidential nomination race as "the strangest election of modern times in living memory".

"It's been absolutely bizarre to see this self-created and baboonish reality TV host [Donald Trump] become the Republican frontrunner," he said.

"I never thought I would live to see a crypto-fascist within reach of the world's most prominent political office.

"It makes me worry but the journalist in me ... is rather perversely fascinated by the strangeness."

Hosted by Julia Zemiro, Theroux will discuss the people and events behind his films seen on BBC Knowledge and ABC during his Q&A-style tour.

"I like to do stories that take me to the depths of what we experience as humans, the most difficult emotions," he said.

"What I take from it is the dignity and stoicism that many people show in extremism.

"I find it oddly inspirational ... it might sounds trite, but finding an unlikely virtue in a place you never thought you would find it."