Marc Thompson was 17 when he found out he had HIV. He had been out as gay for only a year when a friend suggested he get himself tested. “I thought: ‘Yeah, why not? I’m not going to be positive.’ You had to wait two weeks for the results back then – I’d actually arranged to have lunch with a friend on the day they were due, because it never occurred to me that I would be positive.”

Thompson says he will never forget how he felt that day – partly because he is still asked about it all the time. As one of the UK’s leading HIV, Aids and queer black men’s health campaigners, sharing his own experience comes with the job. “I felt complete and utter numbness,” he says. “All I could hear was white noise. I was walking around in a daze.”

By the time Thompson tested positive in November 1986, public consciousness about HIV was growing, but the prognosis was poor and effective treatment was still a decade away. “It felt like a death sentence,” says Thompson. “I spent a lot of time thinking about what it would be like to die in hospital. I picked the songs for my funeral. I planned the most glamorous send-off possible. That’s the way you deal with that stuff in your early 20s.”

Thompson, 52, is very much still here, however. In a 25-year career as an activist and programme manager working in HIV prevention and sexual health, he has been at the forefront of significant changes in the treatment of HIV and Aids. In 2015, he became one of the founders of PrEPster, an organisation that pushed for the life-changing medication PrEP (pre-exposure prophylaxis) – which dramatically reduces the chance of spreading HIV – to be offered on the NHS. After years of campaigning by Thompson and others, PrEP was made freely available in England in April 2020. (It was rolled out on the NHS in Scotland in July 2017, while routine commissioning was announced in Wales in June 2020; after a two-year pilot, Northern Ireland is expected to make PrEP available imminently.)

It is a watershed moment, he says, especially for gay men. “For nearly 40 years, many gay men have carried a fear of HIV on our shoulders that prevents people from loving freely,” he says. “I know men who are PrEP users who talk about being liberated from the fear of sex.”

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I meet Thompson in the LGBTQ+ community space in the housing co-op in Brixton, south London, where he lives with Travis, his parson russell terrier. Rotimi Fani-Kayode, the Nigerian-British photographer who was known for his explorations of race and sexuality before he died of Aids in 1989, used to live in this building, Thompson says proudly. Indeed, it has been home to a lot of campaign “plotting” over the years.

His work as a campaigner began in 1992, when he started going to a support centre for people with HIV and Aids at the Landmark Aids Centre in nearby Tulse Hill. In the early years of his diagnosis, “I wasn’t big on going to social support groups, because invariably I was the only black person there, invariably the youngest, and more often than not the only person who wasn’t unwell. I felt really isolated.”

However, an opportunity came up to run workshops on safer sex for black gay men. “This was a new concept at the time, you know: how are we getting people to use condoms properly? So I jumped on board. It was fun. And I realised that by telling my own story and talking about my diagnosis and how I came to terms with my sexuality, I was giving people permission to tell theirs, too.”

In 1995, he joined Big Up, a group set up to address inadequacies in the HIV prevention services available to black gay men. At the time, services were either aimed at white gay men or straight black communities. “Neither of them were doing work for black gay men. So we fell through the cracks.” It is an area he has stayed in for the simple reason that the work is necessary. Despite a dramatic reduction in HIV transmission rates in recent years – new diagnoses among gay and bisexual men in the UK decreased by 47% between 2014 and 2019 – black gay men are 15 times more likely, globally, to get the virus.

“If we look at the drop in the rates of HIV diagnoses in men in the past few years, they’ve been incredible, but we haven’t seen the same drops for men whose first language isn’t English, men who are migrants to this country or men who aren’t white,” says Thompson.

“I fight for all communities, but I make no apologies for putting black gay men at the top, because we’re so often on the bottom rung of the ladder,” he says. “I have no doubt that if the Aids epidemic had hit young, white, straight people at that time, the response would have been different. The government and the health service would have acted a lot more quickly.

“You see the same with Covid today; we’re still asking why black and brown people have poorer health outcomes.”

Thompson was born and raised in Brixton. His father was a demolition worker, instrumental in clearing London of the postwar rubble that gave way to a vibrant new city. His mother was a probation officer, working with south London’s young offenders.

“I’d love to say my activism was inspired by Martin Luther King or Bayard Rustin, but it wasn’t,” he says. “It was inspired by the regular people that were around me – my dad, my mum and my grandparents.” Both sets of Thompson’s grandparents migrated to the UK from Jamaica. “It was that typical story,” he says. “My maternal grandfather came here in 57, then sent for my mum. My paternal grandparents settled here and then went back to Jamaica in the mid 70s, but their children stayed here.

“Observing my dad and uncle’s experience of police brutality, stop and search, and the unfairness my mum faced as a black woman in the 70s gave me an early sense that there was injustice against black people in this country,” he says. “My dad was a really proud man who told me to stand up straight and walk strong in this world. Hearing those things throughout my childhood made me acutely aware of my position in this country.”

Thompson came out to his mother when he was 15, who was “brilliant”. “There’s a narrative of black families not always accepting gay children,” he says. “My family accepted my sexuality, they accepted my HIV.”

Navigating the homophobia and racism of London in the 80s was more difficult. “I was out to my family, but I wasn’t out in my barbershop,” he says. Meeting other gay people locally helped. “I was lucky. So many gay men come out and they don’t know where to go. That was especially true for black people, because those spaces either didn’t exist or they were underground.”

Going to black queer club nights, such as Queer Nation in Vauxhall, was a “political act” he says. “We fell in love in those spaces and expressed ourselves, and that became so important as the Aids epidemic started to take root. The club became our salvation.”

The importance of that salvation was brought to life vividly this year by the Russell T Davies drama It’s a Sin, which spans the often too-short lives of a group of friends in London during the Aids epidemic. The show, which is Channel 4’s most-watched drama ever, has been “fantastic in reigniting the conversation around the epidemic in our communities,” says Thompson.

“I’m encouraged when I think about all the young people who have been inspired to find out a bit more about their history. But I don’t want young queer people to worry about HIV like we did.

I know people who’ve been diagnosed recently, who are young. They’re just as devastated as I was 35 years ago. What’s different is there’s so many more options to prevent HIV [transmission].”

There is still no cure for Aids, but there are treatments for HIV-positive people that enable them to live long and healthy lives. Antiretroviral therapy (ART), which stops the virus from reproducing, did not arrive in the UK until 1997. Thompson began his in 2001 – 15 years after he was diagnosed.

As an HIV-positive man, Thompson will never take PrEP, but it is a key part of his holistic approach to preventing further transmission: “I now have two new ways to help people prevent HIV transmission. One is prEP, one is U=U.” The latter, “undetectable = untransmittable”, refers to HIV-positive people with a viral load so low, thanks to ART, that they won’t be able to pass on the virus through sex.

“When we started the PrEP conversation, it was very similar to the HIV conversation in the early 80s. ‘If you don’t want HIV, don’t have sex,’ became: ‘If you don’t want HIV, you should just wear a condom,” he says. “As a man who’s already been diagnosed with HIV, I don’t necessarily need to spend energy promoting prEP; I could just promote U=U,” he says. “But I see the two as going hand in hand, because I want negative and positive people to be safe and liberated.”

“The fact that PrEP is available in sexual health clinics is great. It means that, if you’re an urban, gay man, you can get it. The challenge we’ve got is for those communities who are still at risk: women, black African communities and trans people,” he says. “We need to raise awareness, but also put it in places where they can access it – so how we can get PrEP into GP clinics and pharmacies? That won’t just help black African women; it will improve access for everyone, including young gay men.”

The UN Aids target, which has been adopted in Britain, is to reach no new HIV transmissions by 2030. “We’re doing a good job of testing our way out of it in this country, but the issue is that it is a global pandemic, not a UK pandemic, and if we keep cutting foreign aid, we are never going to end HIV,” he says.

Thompson says he hopes that, in 35 years’ time, “we’re no longer talking about HIV”. Given that, in 2016, 438 children were infected with HIV every day, this is an ambitious aim.

Still, he will keep going. “HIV opened my eyes to so much,” he says. “It’s given me a career and introduced me to some of the most amazing, inspirational people from all over the world, but above all it’s taught me that, whatever life throws at us, we all deserve to be loved for who we are.”