"We should probably start, shouldn't we," Louis Theroux says, after quick-firing several rounds of questions to myself, the photographer and the publicist sat in one of BBC Broadcast Centre's cramped meeting rooms: "Where do you live? How did you get here? What are your offices like? Do you have kids?"
"What's your surname again?"
I wondered how Louis Theroux-like he'd be in real life, off-camera; whether he'd come in, extend a hand and say, quite loudly, as he does: "Louis. How do you do?"
He did, of course. And, over the next hour or so, there's very little to distinguish the prolific documentary maker's on-screen presence with the man sat gently sipping a giant mug of tea – save the facial hair, which is pretty thick again these days. He rubs it a lot as he talks.
Theroux's new BBC2 series, By Reason of Insanity, takes place in a secure psychiatric hospital in Ohio. He spent a month there, building a rapport with patients who, in most cases, were there because they'd inflicted gross bodily harm – many had killed – in the throes of psychosis, and were being helped to rehabilitate. The majority are diagnosed with paranoid schizophrenia. One man, Jonathan, murdered his father because he believed that he'd sexually abused him as a child – something he now accepts didn't happen – and one of the standout moments of the series, perhaps in the last five years of Theroux's filmmaking, is when he poses a seemingly innocuous question to Jonathan, stood rigid and apathetic (we're told later that emotionless behaviour is part of the constellation of "negative symptoms" seen in schizophrenic people) in his small bedroom: "Did you love your father?"
At first Jonathan doesn't really know what to say. But when he and Theroux share what Jonathan flatly calls a "low-cal pop" later on, it transpires that, throughout years of intensive talking and drug therapies, no one had ever asked him such a simple but powerful question. As the camera pans into its wide shot, his face gently opens, like a chrysalis. Theroux had managed to converse with him on not on a clinical or journalistic level, but a human one. "Sometimes you ask a question and you're pushed through this social barrier," he says. "And that was one of them."
This, of course, is what Theroux does. Despite the inherent otherness of the communities he filmed with over the years of his Bafta-winning Weird Weekends series, and despite being criticised from time to time of glossing over moral ambiguities for the sake of a laugh, his skill has always been getting people to say more than they thought they would – or could.
In the beginning his presence was impish, geekily enthusiastic (if you've not already seen it, here he is dancing to Groove Is In the Heart in the 90s with Adam and Joe) and, in his one of his first Weird Weekends, 1997's Porn, Theroux explored the vast pornography industry that existed alongside mega bucks Hollywood movie-making – the cogs of which we'd never really seen this side of the Atlantic. In it, he managed to, in his gently joking manner, get people talking about things like not being able to get a boner on-command or having to do gay porn because the straight porn market was so saturated: day-to-day things totally intrinsic to the industry and its community that we at once guffawed at, but also thought, 'Huh, I'd never considered that.'
Over time, though, there's been a marked shift in Theroux's filmmaking. Once at home embedding with entertaining UFO believers, Las Vegas hypnotists and California swingers – or, indeed, tempering the advances of a sozzled and horny Christine Hamilton – he's now focused on thoughtful and important investigative films. "It's been a very gradual evolution," he says, "and I think it's taken a bit of nudging on my part for my seniors at the BBC to allow me to do different kinds of stories. I've always been interested in more sensitive stories, as well as the humorous stuff, but it's been a case of evolving my skills and also creating the belief here [he gesticulates around the BBC's huge, open-plan office space] that I can do it."
What was the turning point, then?
"Neo-Nazis are quite a serious topic. They're deeply questionable and many of them dislikable. The thought process with that was, 'Okay, there'll still be some comedy there,' but when you're working with damaged women, how much humour can you possibly create? It was a leap of faith."
The next pivotal pieces for Theroux, he says, were Louis Theroux: Behind Bars – a documentary about one of America's most notorious prisons, San Quentin – and A Place for Paedophiles, which saw Theroux become the first filmmaker to ever have been granted access to film inmates at Coalinga State Hospital, where sex offenders who have been deemed unsafe for release are living and receiving treatment. In his personal wrestling with whether he can believe the words of men whose entire histories have been defined by deceit and deception – "there were little bits of humour there, but not much" – it was, he says, "quite a big change." Then, with a film like Extreme Love: Dementia, exploring the shadowy worlds of those with degenerative brain disease, there was no real questionable moral dimension at all. "Everyone was acting completely in good faith, in an informed way, in the best interests of everyone else," says Theroux. "Suddenly, I was no longer going along with people where there's questionable practice, and, rather, just exploring very difficult decision-making to do with people's lives."
His newest film, Transgender Kids, concerns decision-making on a life-defining level. Filmed in a San Francisco hospital that's pioneering the treatment of kids who say they've been born into the wrong body, it's an investigation into a landscape that's moving as we speak and is bound to be met with some controversy. "That makes it quite a hard story in a way, because there's an urge to try and be definitive," says Theroux. "But we're still in the process of figuring out what the best practice is in these situations, where someone's gender is either unclear to them or is in some way unclear to the people around them based on the fact that the person's so young, and that maybe they're not the best judge of exactly who they are at that point."
Alongside conversations with teenagers in various stages of transition – many are taking hormone suppressants to delay the puberty that would come with their birth gender, with full support of their parents – Transgender Kids visits kids as young as five. Five-year-old Camille, for example, was born male, but her parents have accepted that she is now transgender. In one touching scene, Camille twirls about her twinkling bedroom and pours Theroux a "cup of tea" (a plastic cup full of sparkly pencils). He takes a sip, "Mmm, that's delicious." She is comfortable and firm when he asks, gently, if she'd ever want to be Sebastian again. "No. I would never do that. Always be a girl, always."
It's a magic moment that pierces the artery of shifting transgender politics. If we can help those kids who are definitive about who they are at such a young age – the clinical psychologist at the hospital speaks of meeting two-year-olds who become angry when their parents soothe or congratulate them with the wrong pronoun – the underlying message is that their prospects are far greater. Theroux says he hopes his approach comes across as nonpartisan, though. "There are prejudices that come from different ways of looking at it, and we can all read it in different ways. To some extent, it's deliberately a bit open-ended."
What might some of those prejudices be?
"In some cases there's a kind of unspoken dimension to this story, which is to do with effeminate gay men being mis-categorised," he says, choosing his words carefully. "Some would argue that what they are is trans women. Its usually controversial and I'm not suggesting for a moment that this is the case. With small kids it's exceptionally hard to know."
One kid in the film appears to be fluid in her identity – mostly identifying as Crystal, a girl with a fondness for silk kimonos ("they feel very nice") and sequinned dresses, but also identifying as Cole, a boy who speaks of growing up a man and having a wife and two kids – which I sense is who he is referring to. I tell Theroux that, in certain moments throughout the film, I thought, 'You might end up being an effeminate gay man when you're older,' about Crystal. "Yes, but again, it's very hard to know," he says. "Some kids might be expressing themselves in that particular moment in their lives as wanting to be a woman or a girl. But they're very young."
"It's really hard to know isn't it? he continues. "For me the big question is about the spectrum of gender, and how people can fall anywhere on that spectrum. You hear a lot about sexuality and, with something like bisexuality, the spectrum is acknowledged. But that is – clearly – equally the case with gender. The spectrum is something you can move around on." He says that no part of his film is trying to "pull away the outer bits and find the solid core," because the core "is up for grabs."
He takes a much stronger, definitive stance on the idea of what the doctors at the hospital are doing for these transgender kids. "This is definitely not reparative therapy," he says. "It's something much more subtle and deeper, to do with how we choose to express who we are and how that influences our differences. Reparative, or what people call 'conversion therapy' is massively destructive and is concerned with the idea that you can, somehow, make all gay people straight. Massively destructive."
Filming with such young kids, he says, made him "a little bit nervous", because it's "a higher stakes game – obviously they are more vulnerable." In this instance, too, decisions are being made, to an extent, on their behalf. "It's a hard decision to film with them and put them on display in a way, so you really have to think that through. It sort of hinges on my ability to build rapport and go on a journey with them."
Presumably, if a kid's not into it, they'll just bugger off. "Yes, and go and hide in a cupboard or something. When a kid is bored they just won't play the game, which makes it that much more valuable, I think, when they are comfortable and telling you something real."
Navigating vulnerability has always been key in Theroux's approach to his subjects. Has he ever, looking back, pushed people more than what was warranted?
"Yeah, I think I have actually," he says. "I worry generally when I think about how I've either not pushed it enough or have pushed it too much. But that's part of how it works. When you're talking about people who are viewed in some way as pariahs, there's a school of thought that says, 'Get the goods on them, give them a figurative kicking and then we'll be alright in viewing it,' but on the flip-side, notwithstanding their beliefs, these people are human.
"It's like that Nigel Farage thing," he continues. "People were applauding the protesters that stopped his lunch with his family. But I thought that you behave decently to people, even if you regard them as contemptible in some way. I applauded the guy who tried to make a citizens arrest on Tony Blair because he was at a public forum and, with Iraq on his conscience, to me that's kind of different." He pauses. "That's not to say that anyone should have disrupted his lunch, though."
Theroux says he finds it "deeply annoying" when you see someone who is "not informed or spreading misinformation" and is not being called out on it by the journalist in question. "People questioned me for covering the Phelps family [The Most Hated Family in America]," he says, "and because it was seen as so offensive, people said things like, 'Why would you even interview them and give them a platform?' but I feel like the proof is in the pudding, you know?"
"Well, you have to bring your best game, otherwise it is irresponsible. If you're going to watch a piece on questionable characters, you want them to be challenged."
Conversation turns to his now infamous interview with Jimmy Savile (When Louis Met... Jimmy) that took place 15 years ago. There is, retrospect, untold menace when he says, "It's easier for me, as a single man, to say, 'I don't like children' because that puts a lot of salacious tabloid people off the hunt." Theroux has spoken recently of how he wished he'd pushed him further. "I thought: 'He's got something he's keeping from me.' But then that in itself was his modus operandi. He used to tantalise you by giving the impression he did have secrets... I knew that he wasn't being totally upfront about what his was. But I didn't know what it was and I wish I had. I would have pursued it much more aggressively," he told the Guardian – and how he "felt like a pit bull, gnawing away at him."
Watching the interview back at a later date, it seemed to Theroux that Savile was close to tears.
"I really gave him quite a hard time about his mother, asking why he kept her clothes and dry-cleaned them every year. I slightly forgot that we were in this room that was very special to him and his relationship with his mother was almost..." he grimaces slightly. "It was over the top. He kind of venerated her. And then of course subsequently, well, everything came out. It felt like I was going in too hard but then you think, well, I should have gone in harder."
The momentum of self-revelation – both his subjects' and his own – is, you sense, an evergreen fascination of Theroux's. At one point in Transgender Kids, he tells one of the teenagers – expressing some discomfort about how she's going to navigate the rest of her life – that, between the ages of 14 and 15, he'd never felt "more profoundly alone" and that it was "one of the most difficult years of my life." He feels a bit odd about this now. "I have mixed feelings about that being in there. A tiny part of me questions how appropriate it is, but at the same time it came from an honest place, so I feel kind of fine with it."
Theroux's over-analysing this, I think. It feels incredibly natural in the film and the young girl's face visibly softens when he says it – it's a genuine moment of shared human experience. He talks about not "forcing" these things, but is he this cautious about bringing his own anxieties under analysis in general, not just in relation to his filmmaking?
"I have the normal feelings of anxiety and managing my emotions in life, which is inherently stressful," he says. "I'm very stable, I think. I've made no secret of the fact that I've seen a therapist a few times over the years, but I absolutely see that as taking your car into the garage and having a look under the hood."
Of course, as a society, we've become experts at medicalising daily life and normal emotions – an "urge" Theroux says he "actively tries to resist."
"It's a massive area of debate, especially in America," he says. "Are we over-medicalising normal emotions like grief? I think we might be. I agree with the removal of the Bereavement Exclusion from the diagnosis of depression because, if you're sad and depressed and can't get out of bed and someone says, 'Is there anything else going on?' and you say, 'Yes, my wife of 30 years has just died,' well... there you go. That might help explain what's going on."
"Life is full of mysteries," he says, waving his arms about. "We're all just trying to get the best out of it, dealing with our very normal emotions along the way. So yeah, I feel mentally very healthy."
What will Theroux do next? He doesn't seem to have a clear answer. "There's no definitive plan," he says, squinting against the sun rays bouncing off the roaring Westway below the Television Centre balcony. After all, he's always presented his career in television as a kind of happy mistake. After Oxford, where he got a first in History, he applied for a job working on Michael Moore's series TV Nation because he wanted to work on the show – not on-screen generally. Presumably the accent and his inherent inability to not ask the hard questions made him quite the hot ticket. Rumour has it that he's working on a full-length film about Scientology, although his publicist at the BBC advised me not to ask about it, seeing as nothing had been confirmed. But his Twitter call-out for Scientologists last February suggests it might be in the pipes.
Let's hope it's true. The complex vulnerability of his recent subjects have seen a more cautious, graceful Theroux come to the fore, which is brilliant, because who else would take a leap of faith in filming a subject as sensitive or prudent as young transgender children? But it'd be thrilling, at some point, to see the "piranha of interviewers" – as Savile once referred to Theroux – nip away at the 20th century's murkiest, most controversial religious moment. Because if there are secrets to be revealed, he'll be the one trying to lift the veil.
'By Reason of Insanity' Parts 1 and 2 are available on BBC iPlayer. 'Transgender Kids' will be broadcast on BBC Two on Sunday 5th April at 9PM