The night I saw Grenfell, the play by Gillian Slovo based on interviews with survivors of the Grenfell Tower fire, there was a small but unprecedented response from the audience. On paper, Grenfell, which has transferred to New York after its successful run in London, is a tough sell to American theatregoers: the disaster wasn’t big news in the US and the play’s setting is peculiarly British. Towards the end of the play, however, when a survivor suggests the fire wasn’t caused by the system being broken but rather by the system performing exactly as built, the audience at St Ann’s Warehouse in Brooklyn broke into spontaneous applause. “We haven’t had that reaction before,” says Slovo. The 72-year-old playwright and novelist is accustomed to chronicling failures in government and if the subject matter of Grenfell seemed, at first glance, more parochial than her verbatim plays about Guantánamo or Islamic State, it turned out to be deceptively so. The deaths in 2017 of 72 people in a west London tower block tell a universal story, not only about deregulation and corporate carelessness, but about double standards in government towards marginalised communities. Any American who can summon images of the Lower Ninth Ward in New Orleans after Hurricane Katrina – people left to fend for themselves; people shot at by police as they fled, or camped out on sidewalks – can understand immediately and viscerally what this play is about. The playwright herself feels these issues particularly keenly after a lifetime considering imbalances of power. Slovo’s body of work, and her background as the child of two titans of the anti-apartheid struggle in South Africa, has perhaps given her a reputation as earnest. On the evidence of our interview that’s not the reality at all. At a restaurant on Manhattan’s Upper West Side, Slovo is quick to laugh and point out the sheer pleasure and privilege of learning about other people’s lives. Much has been made of the horror of the stories emanating from Grenfell; less remarked upon is how funny the play and its characters are. “We wanted an audience to understand that these are individuals with their own histories and way of being,” says Slovo. “To know what it is to be in a burning building and have to get out – you need to know who those people were, and a bit of their history.” Slovo characterises herself as a nerd; conscientious; happy in her own head; occasionally people-pleasing, particularly if the person in question was a parent. The author of 16 books and one memoir never thought she’d be a writer and studied science at university, which, she says ruefully, was because “I was a compliant daughter. My mother wanted a scientist in the family and I was the only one who stood a chance.” She laughs. “Not much of a chance, actually.” Standing up to your mother is hard at the best of times. But Slovo’s parents, Ruth First and Joe Slovo, were icons. Beyond that, her mother was a very particular type of sharp-tongued South African woman with no patience for the lesser mortals around her. The story of Slovo’s upbringing and the aftermath of her mother’s assassination in 1982, via parcel bomb sent by the South African security forces, is one Slovo told in her 1997 memoir, Every Secret Thing. If she retains the mannerisms of someone who is vaguely watchful and wary, the evidence for why is all there. It also explains the bent of her professional interests. “I am attracted to subjects that contain a lot of pain,” says Slovo, who was 30 when her mother was murdered. “It’s because I think I understand. I can relate to it. It doesn’t scare me. I don’t feel it’s something you should run away from or cover up.” She is very conscious of the boundary between interviewer and subject. When Slovo spoke to the survivors of Grenfell, six months after the fire, she was keenly aware “that it’s not my pain, it’s theirs. And that I can do something by bearing witness, and helping them bear witness in public. The big thing was that nobody listened to them. So I can listen. And I’m interested in listening! I feel very caught up when I’m interviewing people because I really am learning something.” The modesty of this description is accompanied by a straightforwardness that clearly pays dividends. In the context of persuading people to talk, there are no sleights of hand that work better than being sincere. “My experience is that some people will talk to you and some people won’t. And you can’t really persuade people who don’t want to talk to you.” For those willing to talk, says Slovo, “I do feel that if you are trustworthy people will get it.” I find myself curious about the relationship Slovo’s daughter, who is in her late 30s and was born and raised in England, has with her mother’s family history. Slovo was 12 when she moved to London, and it was a shock. A child of suburban Johannesburg, she had never even been on a bus on her own and, at her comprehensive school in north London, was teased for her prissy posture and teacher’s pet attitude. At the same time, she was coming out of a childhood of considerable trauma, one in which her father had been frequently absent on revolutionary business and her mother in and out of jail for the same reason. I wonder how close any of this is to her own child? “I think it’s very real to her. When she was eight, we went to live in South Africa for a year while I was writing my family memoir, so that was quite formative to her. That was South Africa at the best it had ever been, and” – she hesitates – “possibly will ever be. Because people were so full of life and change. And ‘we can do this.’” And of course the family name comes with baggage. “My mother’s death affected me for a very long time, and she was born into that,” says Slovo. “So I’m afraid she carries some of that. I tried to keep it from her, but I don’t think you can. The family reputation in South Africa is so large.” I remember driving, many years ago, down Joe Slovo Drive, a major arterial road that cleaves through the centre of Johannesburg, and wondering at how odd it must be for the family. (Ruth First has her own memorial highway further south). Yes, says Slovo. “My daughter has to negotiate that, just like I did. I mean you have parents who set out to change the world. And they actually succeeded in changing the world.” She smiles. “You can feel yourself to be a bit inadequate. I was brought up among giants.” The passion for social justice is, she says, “transmitted through being part of this family”. But when Slovo first started writing, it wasn’t the main impetus. “I started writing to see if I liked it. And I really liked it. And of course when you start, you don’t understand how difficult it is. You just think you’re brilliant for getting the words down.” Her first novels were detective fiction and that has helped, she says, with understanding how to structure the verbatim plays. Harder to learn in some ways has been how to adjust to working in a team. Novelists involved in collaborative projects often talk about the joy of other people. Slovo looks sheepish. “I do love sitting at my desk, writing on my own. That’s why I became a novelist. I … really like being on my own. I’ve had to learn to be with people.” The rule of thumb for any verbatim play, she says, is “you can do anything, as long as you do right by the people you are representing and it works for the audience”. And while Grenfell has a short run in New York, it strikes me as a play that is just as relevant and accessible in the US – or anywhere else at the mercy of the same political forces – as it is in the UK. As Slovo puts it, it is about “the deregulation of our world and the carelessness of people who don’t think ‘if I do this wrong somebody might die’”. As the playwright knows as well as anyone else, it is also, simply, about people; who you become, for how long and to what effect when something terrible happens. “The kind of trauma that lasts your whole life.” Grenfell: In the Words of Survivors is at St Ann’s Warehouse, New York, until 12 May