The new Penguin edition of Linton Kwesi Johnson’s Selected Poems comprises three previously unpublished verses, the most recent of which is titled Di First Lackdoun. Written in August 2021 in his signature style – London-Jamaican patois rendered as it is spoken – it recounts a walk he took in his local park in Brixton as the long weeks of the first winter Covid gave way to spring.

people juss skattah like littah
all ovah di clean-cut carpets of green
redeemin ert an sky an sunlite

some a sit inna wide wide circle
like in some aintshent tradishan
a ritual of revahrence to life

The poem is joyous, celebratory and brimming with an almost childlike sense of wonder and uplift. Until, that is, the last line, when the music and laughter of the socially distanced sunbathers, cyclists and skateboarders he has encountered is suddenly drowned out by an all too familiar noise – “di unrelentin wailin soun of sirens” from passing ambulances.

“The lockdown was extraordinary,” he tells me, as we sit, sipping iced water, in the sunny backyard of a bar in Herne Hill, “because most nights you could not hear a sound. In Brixton! But by daybreak it would start again and, from dawn to dusk, it was just sirens. Ambulances going up and down, up and down.” He pauses for a moment as if transported back there. “Lambeth got hit hard, but touch wood I was all right.”

How did he deal with the long months of enforced isolation? “Well, I feel as if I lost two years of my life somehow,” he says. “I’m almost 70 and just when I should have been going about enjoying myself, this thing happened. And, after a while, I got lazy. And, what’s more, I got to like being lazy – sitting at home all day, watching rubbish on the telly, going for walks in the park. I had a little routine and I got too used to it.”

Dressed for the hot weather in white T-shirt, baggy shorts and sandals, rather than his signature suit, tie and trilby, Linton Kwesi Johnson does not look his age. He is sprightly, more animated and mischievous than the serious young activist whose spoken word reportage, delivered over hypnotic reggae rhythms, almost singlehandedly defined the term “dub poetry”. On a quartet of groundbreaking albums made in collaboration with producer Dennis Bovell – Dread, Beat an’ Blood (1978), Forces of Victory (1979), Bass Culture (1980) and Making History (1983) – Johnson recited the words of anger, struggle and defiance he had written to the pulse of reggae bass lines he heard in his head. Many of those spoken word songs remain resonant today: Mekin Histri, a protest poem against police and government corruption; Liesense fi Kill, which tackles the deaths of young black men in police custody; Five Nights of Bleeding, a visceral evocation of the internecine violence that could erupt without warning at a blues dance or a reggae gig – “cold blades as sharp as the eyes of hate”.

“I was trying to find a bridge between standard English and spoken Jamaican,” he says of his initial decision to express himself in the vernacular of the London-Jamaican community to which he belonged. “A lot of poetry of the time sounded like Caribbeans trying to sound American, a bit like those Mick Jagger songs where he’s trying to sing like he’s from the deep south. For me, what was important was authenticity of voice. I didn’t want to emulate anyone else. I wanted it to sound like me.”

In his introduction to the new edition of Johnson’s Selected Poems, the author and political journalist Gary Younge recalls “the thrill of transgression” he felt as a teenager in the 1980s when he watched Johnson recite Inglan Is a Bitch on television. “I didn’t know you could do that,” Younge remembers thinking, “effectively say what you’re thinking about racism in Britain out loud in public and still work again.”

Others were not so thrilled by Johnson’s audacity and linguistic iconoclasm. In 1982, in the wake of the first Brixton riots, the Spectator railed against his phonetically transcribed patois poems, claiming they had “wreaked havoc in schools and helped to create a generation of rioters and illiterates”. Never one to seek mainstream or literary validation, Johnson’s politically anchored self-assurance was unshakeable in the face of such loaded criticism. “From the start, I saw my verse as a way of chronicling black British history as it was being made,” he tells me. “I certainly did not see myself as an angry young black poet, which was often how I was portrayed, but as someone who was attempting to articulate in verse the experiences of my generation.”

The artist and film-maker Steve McQueen recently used Johnson’s angry elegy New Craas Massakah in an episode of his acclaimed BBC drama series Small Axe. It was originally written in the wake of the 1981 New Cross house fire, in which 13 black teenagers died from a suspected arson attack. The young poet and critic Kadish Morris, who first encountered Johnson aged 13, when he came to a poetry workshop in Leeds organised by her mother, recalls the visceral charge of the poem in the context of McQueen’s film. “It was so powerful and raw to hear the poem over footage from the time,” she tells me, when I ask if his work still resonates with a younger generation of performance poets. “Everyone was on Twitter afterwards asking, ‘Who was that poet? What was that poem?’”

McQueen also commissioned a new poem, Towards Closure, from Johnson, for his recent documentary series, Uprising. It is the final poem in the book, a short, moving tribute in plain English to the memory of the victims. “It was perfect and it was powerful, because Linton has stayed true to the truth,” says McQueen. “The truth is his fire. And the truth is dangerous, but he knows how to handle it. It’s very difficult to do that as an artist, and for it to be piercing, but the truth vibrates through his words and his sound. There is a clarity to it.”

* * *

The Penguin volume neatly divides Johnson’s verse into three chronological sections: the 70s, 80s and 90s. “The first decade was about urgency of expression, things I needed to get off my chest,” he says. “The second was all about learning my craft and how to structure my language, and the third was when I finally began to find my voice. I’m a classic late developer, so it took me 20 years to get there.”

Was it difficult to decide which poems made the final cut? “It basically came down to how embarrassing they were to read again,” he says, laughing. “If they weren’t cringeworthy, they stood a chance.” Are there others that, with hindsight, bring him a sense of deep satisfaction? “That would be going a bit far. I’d say there are maybe five or six good poems in there and the rest I can live with.”

Johnson’s modesty underplays his artistry, as well as the lasting cultural importance of his work. He came to poetry, he writes in his afterword, “from the backwoods of literary ignorance”. Born in the rural small town of Chapelton in the parish of Clarendon, Jamaica, he travelled to London in 1963, aged 11, his mother having made the journey before them. “I come from Jamaican peasantry,” he says, matter of factly. “My family were subsistence farmers, so basically we ate what we grew. Once in a while, we might have a few extra eggs to take to market, or some sugarcane or ginger. That’s how we lived.”

He remembers as a child being enthralled by “nonsense rhymes, skipping rhymes and Anansi stories”, as well as the Bible verses he learned by rote at school. “You could say that I was well grounded in the Jamaican oral tradition by the time I left.”

His activism began when he joined the youth wing of the British Black Panthers when he was still at school. What did that entail exactly? “Political education. You had to take part in demonstrations, sell the newspapers and study certain texts. We read Soul on Ice by Eldridge Cleaver and Seize the Time by Bobby Seale, but also Capitalism and Slavery by Eric Williams and The Making of the English Working Class by EP Thompson. For us, class was important as well as race in the struggle.”

Johnson went on to study sociology at Goldsmiths, and, for a time, wrote freelance music reviews and penned artist biographies for Virgin Records. In his afterword to Selected Poems, he writes: “Poetry for me was never a calling. It was more like a visceral need for self-expression at a formative period of my life, when I was trying to find my way in the world.”

His poems first appeared in the journal Race Today, which was published by the Brixton-based radical black collective of the same name, which he belonged to alongside his friend, the late Darcus Howe. They were written, he says, “out of the deep sense of alienation and rejection” that his post-Windrush generation experienced in Britain. “In Jamaica, we were schooled to be British, to wave the flag when the Queen came, but when we came here we were othered by the rest of British society. That kind of estrangement was profound and it is one reason why reggae was so important to us. It gave us a sense of independent identity that was all our own.”

Two books followed, 1974’s Voices of the Living and the Dead and 1975’s Dread Beat and Blood, the latter also providing the title for his first album, which was released by Virgin Records in 1978. Made on a budget of £2,000, it signalled much of what was to come. His spoken-word lyrics, anchored and given heft by Dennis Bovell’s deft, dub-wise production, often sounded like warnings from the heart of a disfranchised black British community, whose rage at heavy-handed policing would stoke the riots of the early 1980s in Brixton, Toxteth and St Pauls.

The dub poetry that Johnson created drew on many diverse sources, including the work of groundbreaking black American poets of the 1950s and 1960s such as LeRoi Jones and Jayne Cortez, Caribbean writers such as Kamau Brathwaite and Andrew Salkey, and Jamaican reggae DJs or toasters such as U-Roy, Big Youth and Prince Jazzbo, who improvised over instrumental cuts of well-known songs.

Johnson’s arrival on the British music scene coincided with the birth of post-punk, when groups such as the Pop Group and the Slits were deploying dub-reggae stylings – Bovell produced records for both. On Christmas Day and Boxing Day 1978, Johnson played two shows in support of Public Image Ltd, John Lydon’s post-Sex Pistols group, at the Rainbow theatre in Finsbury Park. “Oh my God!” he exclaims, when I ask him about the experience. “It was just me and some backing tapes on a Revox tape machine facing an ocean of punks. I wanted to run offstage, but, to my surprise, they liked me.”

He toured too, with Ian Dury and the Blockheads – “He was a perfect gentleman” – and Siouxsie and the Banshees – “They treated me real nice.” Did it trouble him, though, that he was performing to almost exclusively white audiences? “Not at all. I saw it as an opportunity because I was talking about the black experience and white people need to know about it. We black people already knew it because we were living it.”

Johnson’s engagement with the music industry says much about his character, self-assurance and the strength of his political ideals. He turned down lucrative long-term record deals from both Richard Branson at Virgin and Chris Blackwell at Island, the man who had helped turn Bob Marley into a reggae icon. Some years later, Johnson tells me, he met Bob Marley’s ex-girlfriend Esther Anderson, who told him that Blackwell had been prepared to spend a million dollars to make him an international star.

“But that wasn’t me,” he says, firmly. “I took myself seriously as a political activist and that kind of life was not conducive to political activism. Also, I never saw myself predominantly as a reggae artist. For me, it was a way to bring my poetry to a wider audience.” He has also, he says, been offered national honours, which he refused. Though last year, he received an honorary doctorate of letters from the University of the West Indies: “As someone who began life as a barefoot peasant boy, roaming about the hills of Clarendon, Jamaica, it doesn’t get any better than that.”

* * *

It is hard to think of anyone in today’s more corporate music scene with such deeply held principles, but, as Johnson acknowledges, “these are different times”. After a lifetime of activism, is he still an optimist? “An eternal optimist. You have to be. There is always hope, even if we seem to be moving backwards in terms of social justice, immigration, poverty. I don’t know how much reading the youngsters do who were inspired by the Black Lives Matter movement, but it is important to educate yourself about what went before because continuity is crucial. You need to know where you are coming from to know where you’re going.”

He tells me he did not vote in general elections until Jeremy Corbyn first ran in 2017: “His manifesto presented me with a genuine choice for the first time.” I ask him what he thinks of the rise of black politicians such as Kemi Badenoch who, when we met, had just announced that she was running for Tory party leader. He shakes his head. “These people are not representative of the black population. They are part of the black elite and their sense of solidarity is with the rich. They do not have any sense of solidarity with black people.”

After our meeting, I walk down Railton Road, where I too used to live in the 1980s, taking in the inevitable changes. The Hamilton Arms, the local we shared back then, is now a supermarket. The all-night grocery-cum-off-licence that once stood on Brixton’s notorious “frontline” is now a minimalist cafe serving fresh-roasted coffee to the young professionals who have colonised the leafy sidestreet. The Rastas and the riots seem so distant as to be a mirage.

Blessedly, the Methodist church and youth club where Linton Kwesi Johnson gave his first live performances is still standing. And the building that was Race Today’s office is now the Brixton Advice Centre, its windows bearing portraits of Johnson and his fellow activists. Round here, even amid all the changes, he remains a local and a legend. “If any young artists need to know about longevity and integrity, he is the one to look to,” says Steve McQueen of Johnson’s singular status in the British black community. “He knew his path and he walked it. His words are still relevant and that reggae bass is still vibrating.”

• Selected Poems by Linton Kwesi Johnson is published by Penguin (£9.99). To support the Guardian and Observer order your copy at guardianbookshop.com. Delivery charges may apply