Most interviewees keep up a best-behaviour version of their public self while the Dictaphone is on, leaving me to work out what they’re really like from the clues they unwittingly drop. Deploying guesswork in order to divine authenticity might sound odd, but I like to flatter myself that I can be quite good at it. have to admit, however, that had Madani Younis stuck to the smooth, PR-friendly persona he greets me with, no private version I might have imagined would have come close to the sweary reformer who gradually emerges before my eyes. The artistic director of the Bush theatre very much wants to publicise its imminent grand reopening, but his subversive side is so much more interesting that in the end I think even he couldn’t bear to keep it quiet.

We meet at the theatre, on Uxbridge Road in west London, just before its relaunch. It smells of fresh paint and sawdust. The builders vacated just a fortnight ago – electrical cables dangle from the ceiling, and there is a palpable air of last-minute adrenaline and first-night nerves. But Younis is smartly dressed, unflappably upbeat, and maintains a word-perfect commentary about every detail of the building as he shows me around.

Some of his commentary could have been lifted from the fundraising pitch he must have had to deliver thousands of times, to raise the £4.3m renovation budget. For example, “Uxbridge Road is the longest road in London and the most diverse in Europe, in terms of different languages spoken down it. To me, that is my mandate, as artistic director. I want to reflect that road inside this building.” Other lines sound like media soundbites; when I suggest fundraising must have been a Godawful slog, he says: “Actually, it’s great way to make new friends. I think one really has to view it like that.”

Who would blame the 35-year-old for his excitement and pride in his new theatre? Five years ago the Bush was an 80-capacity room above a pub; Younis has transformed it into a magnificent venue featuring two auditoria that seat 250 between them, a rehearsal studio and writer’s room, full wheelchair access and solar panels, reclaimed mahogany and exposed brickwork, all designed to communicate to the community that the building – once a public library – belongs to them. “Cultural buildings have a great habit of hiding art from people. So it’s really important for me that this building is porous. It does surprise me in a city like London that our cultural buildings don’t reflect the culture of our city. That still baffles me.”

For the past 12 months, during renovations, the Bush had to be “nomadic”, performing its This Place We Know festival of mini-plays all over the place, in local community centres, and even a karaoke bar. It was a logistical nightmare, but with one unforeseen benefit. After Britain voted for Brexit, a nearby Polish centre was vandalised, hate crimes spiked, “and us being out and about and living that experience in amongst our community was no bad thing. You come back to this building with a sense that it should be a safe space, a home to all the communities.”

I ask if he shares the view some take that Brexit and Trump are good for arts and culture, and he considers the question in silence for six seconds. “Hmm. I do believe that in response to what has taken place we will see a rupture in art, and that rupture will give way to something that will be a form of activism, a way of looking at the world that we may not have been doing of late. I’m looking forward to a rupture, I really am. I think that’s when culture’s at its most potent, when it’s not comfortable with itself. So now is a good time, as an artist, because there is a lot to respond to. There is an urgency in the choices we make.”

‘I want the work on our stage to reflect the world we live in,’ says Younis … a scene from The Royale, a play he directed at the Bush in 2015. Photograph: Tristram Kenton/The Guardian

He knows there is more riding on this building than the fortunes of just one theatre. Appointed artistic director in 2012, he was the first non-white director of a major London theatre [see footnote], and acutely conscious of the responsibility this conferred. “Yeah of course. But it was always bittersweet for me, if I’m honest, that idea that I’d be the first was bittersweet. Because I know there have been great artists who were more deserving than I ever was, and they didn’t get the gig.”

Political theatre goes in and out of fashion, and Younis is deeply dissatisfied with current portraits of the British immigrant experience. “If you were to judge it purely through the lens of British theatre, postwar, you would think that we were marginalised communities, dislocated, working-class, that our women – our mothers and sisters – were these frail figures in our lives. I mean, fuck that man, do you know what I mean? Fuck that. If you were to just judge our experience through the lens of British theatre, I think you’d do a disservice to what my parents’ generation, my brothers and sisters across the country are doing at the moment. I think that’s the challenge.”

He was born and raised in and around London by immigrant parents, his Pakistani father a trade unionist, his mother a teacher and activist from Trinidad. “We grew up watching Horace Ové films, we grew up knowing who VS Naipul was, we grew up knowing who Derek Walcott was.” He studied film at Southampton University, and after completing a masters in Birmingham in 2000, he “wrote to every theatre in London, asking to be an assistant of some kind. The response was deafeningly silent.”

His first major work was Streets of Rage, which he both wrote and staged, about the Bradford riots of 2001. For the next few years, he worked in theatres in Trinidad and Leeds, but the only way he could see to make the work he wanted was to set up his own theatre company, so in 2008 he founded Freedom Studios in Bradford. His 2011 play, The Mill, was classic Younis; performed in a disused Bradford mill, it told the story of the lives of immigrants who had worked there, giving a voice to communities seldom heard in British theatre.

“I want the work on our stage to reflect the world we live in. I want the artists on our stages to feel like the Bush is a place where they can come and say whatever the fuck they want about the world. When I had my own company, a theatre would often programme one ‘black’ show per season, and you go, ‘Oh that’s the black show this year, right?’ I kind of went, ‘Why does that exist?’ I remember in my second season here – the first season I’d really got my feet under the table – I programmed three shows written by three writers of colour, and we sold that shit out. Those shows went on to win significant awards.”

One was Disgraced, a work set around a dinner party in Manhattan attended by a Muslim, a Jew, a Wasp and an African American, which explored issues of race, faith, terrorism and Israel. It won a Pulitzer, and was typical of the artistic director’s taste for intimate dramas confronting universal themes. The Bush has always pioneered new writing, and will reopen with a series called Black Lives, Black Words. A fifth of tickets will cost just £10, and 50% of the new programme is by BAME writers.

These days there can’t be a director in London who doesn’t lament the lack of diversity in theatre. But while everyone says they’re passionately committed to making a change, time and again they say they just can’t find good BAME artists or material. So what is Younis doing that they’re not?

Younis has transformed the Bush Theatre from a 80-capacity room above a pub to a striking venue with two theatres, rehearsal space and writer’s room.

After six seconds of silence, he mutters “Arghh”, followed by another uneasy silence. Is he trying, I ask, to work out how to phrase his answer? “Totally I am!” he laughs. “Totally I am. I’m not struggling to find the answer. Erm. It’s… erm. OK, I don’t know why the British theatre has struggled for so long to reflect the diversity of its people.”

Doesn’t he? He grins. “OK, I do.” And it is? “OK, but can I just frame it in my head?” Is he trying to work out how to frame it so as not to cause offence? After another wary silence of seven seconds: “I’m trying to frame it in a way which is … hopeful.”

Why? “One wants to be helpful.” I agree that he wants the current state of affairs to change, of course, but don’t know why it should fall to him to find a positive spin. Surely it can’t be his responsibility to make nice, can it?

“I know you know I have an answer to your question,” he laughs, but still won’t say. “Oh it’s such a fucker, such a fucker,” he whispers under his breath. He thinks, tries again, breaks off and laughs. “It’s not that I’m squirming, I just … ” Then, just as I think he’s about to abandon the question and move on, he says:

“OK, diversity is a euphemism for the word ‘black’. The corporatisation of diversity now means that it becomes something we talk about in ways that we feel comfortable. But we’ll never talk about the idea of race. That is actually what we’re talking about. And the irony is that the diversity debate has been co-opted by white men and women. It no longer has its political drive under it. It has been neutralised in the sense that we’ve forgotten about the politics that underpin the idea of racial politics in our country. And that for me is significant. That is what I’m talking about. I’m talking about the politics of race. I’m not using the corporatised idea of diversity.

“I get invited to give various speeches at various things, and I was invited to give a speech to a group of marketing executives. I’m met by a room of 99% white men and women. This idea of how do we diversify our audiences came up. I’m like, surely the first question you should begin with is: ‘How do we diversify our teams?’”

I ask if he thinks the white theatre establishment perceives him as a threat. After another long, agonised pause: “I wish we knew each other outside of this interview. I wish I could tell you away from that,” he laughs, nodding to the Dictaphone. I try again; what is his self-censorship trying to protect?

“Look, I’m aware we’re about to announce this building and my opinions are always vocal and loud. But OK. When I started out, I think people were uncomfortable when I made statements like, ‘We’re not actually talking about diversity – actually what I’m speaking about a lot of the time is how to deal with your white fragility. Because that’s what I’m really helping you to understand, how I can make you comfortable with your white fragility.’ For the most part, that’s what I’m dealing with. The idea of white privilege, the idea that me suggesting the world should look more diverse somehow doesn’t include you. Or that I’m suggesting somehow you are past your sell-by date, no longer are you relevant, there is a new dawn that doesn’t include you. And that is not what I’m saying.”

Does he think the white theatrical world genuinely wants their companies and audiences to look more like him? This time the pause stretches to seven seconds.

“I think, as a child of immigrant parents and someone who isn’t white, the sense of feeling like the ‘other’ remains today. You turn on the news, you read the papers, you’re reminded every day in this country of how you are made to feel that you are either the problem or that you are not welcome here.” There is a fashion for directors to keep their awards in a downstairs loo, but Younis’ bathroom door is papered instead with the pink slips police issue after every stop-and-search. Every time he flies to New York he gets pulled aside, interrogated and searched, without fail. “Unless if I’m there with one of my white colleagues – no problem at all. We breeze through. Neither of us gets stopped.” As for the anti-radicalisation programme Prevent, “Well, kiss my arse. Because I have been the subject of it, and I don’t enjoy it. I just think it dehumanises us, man. When this country reminds us every fucking day, man, do you know what I mean?”

If the government is serious about community cohesion, “more can be achieved through culture than through any fucking government policy, man.” How will he measure the success of the new Bush? Partly in ticket sales to non-white theatregoers, he says. “But it’s also about what these buildings are reflecting back. We have to see ourselves in our art.

“You encourage me to be honest. Well, this is me being honest. My personal mantra is that I want to fuck up culture. What I really mean is, I want to provoke culture – by provoking culture, I feel that will make us more human. And if we’re able to be more human with each other, we’re able to see each other in ways we can’t ordinarily. It’s by creating that rupture in culture that we reveal our true humanity to each other. It’s not about the best version of who we are – it’s about the rawest version of who we are.”

• The Bush Theatre reopens with Black Lives, Black Words on 23 March, followed by Guards at the Taj from 7 April.

• This article was amended on 22 March 2017. An earlier version said Madani Younis was the “first non-white director of any London theatre”; though he has frequently been described in those and similar terms, other theatres in the capital, including the Arcola in Dalston and the venue run by Tara Arts in Earlsfield, had non-white artistic directors before Younis’s appointment at the Bush.