Switchboard, the LGBT helpline, took its first call from a tiny office in the basement of a bookshop in King's Cross on 4 March 1974. To mark the 45th anniversary, people have been sharing memories of a charity that's helped millions across the world.
Lisa Power used to think of herself as a supporter or ally of the gay community, rather than a member.
But in 1976 at a march in Lancashire protesting against an employee at a BHS department store losing his job after coming out as gay, Lisa "accidentally" revealed herself as a loud and proud lesbian.
"Somebody handed me their placard while they went to the loo… I didn't even see the photographer from the local paper," she says.
"The next thing I know there's a big photo in the local paper with me carrying a placard saying 'BHS unfair to gays'… oops!"
After that Lisa thought she "might as well" go along with her new identity.
She's been a sharp-tongued LGBT activist ever since.
Lisa joined Switchboard in 1979, as the gay liberation movement made waves across the world.
Although homosexuality was partly decriminalised in England and Wales in 1967, British culture had not adapted fully to the change.
People continued to face discrimination at home, at work and in public.
After a meeting in a pub between several gay groups across London, Switchboard was set up to cater for the needs of people who needed information or an understanding ear.
Lisa, who now lives in Cardiff, describes the helpline as being "gay finishing school where you learned about everything".
Each shift, volunteers answered calls varying wildly in subject matter and tone.
The caller might want to know when certain gay club nights were happening.
Or maybe the call had come from a giggling group of teenagers, squished into a phone box, having persuaded each other a hoax call would be a laugh.
Or sometimes, the caller would be on the brink of suicide.
The responsibility Lisa had as a listener really hit home while on holiday in Greece with her girlfriend.
A woman who'd been sitting near her on the beach came up to her to thank her for being the first person she had ever spoken to about being gay.
"She'd recognised my voice, she remembered my name, and she wanted to tell me what a difference that year had made," Lisa says.
"That's why we did it."
Lisa, who went on to found the charity Stonewall, adds: "Switchboard gave me the motivation [to be an activist] because you would come off shift sometimes just feeling utterly bloody angry at the lives people were being forced to live.
"The unnecessary stultification of people's lives, people who were just too scared to tell people they were gay."
One of the callers to Switchboard at around this time was a confused 12 or 13-year-old boy called Mark.
Mark Gatiss wasn't to know he would grow up to be a household name as an actor and writer.
Back then, all he was worried about was that he could not say out loud what he knew in his heart.
"I knew I was gay," he says. "I just wanted to talk to someone about the actual experience.
"I lived in terror of [coming out]... what I was afraid of was judgement. I couldn't conceive of a moment in which I would actually say it.
"I was from a very solidly working-class north-eastern background in which such things didn't happen."
He decided to call Switchboard after seeing a poster with the number on it in the ITV sitcom, Agony.
After hanging up on the volunteers several times, he eventually said down the line: "Hello, I'm gay."
"There's a sort of affirmation there," the Doctor Who and Sherlock star says. "There was no-one else to say it to, except, you know, in the bathroom, in the dark.
"They often say you can probably unburden yourself more to a total stranger than to an old friend because there's no comeback, there's no judgement," he says.
In the early days, Switchboard was a small organisation, and volunteers had to adopt underhand tactics to get the number out to as many people as possible.
Groups of gay activists would sneak into libraries across London and stick the Switchboard number "into any book they thought a young gay man or lesbian might go to to read," Lisa says - such as on to pages of the Bible expressing anti-gay sentiments.
But at the start of the 1980s, everything changed.
Scientists began to notice a sinister rise in deaths in previously healthy, young gay men.
The HIV epidemic had reared its ugly head.
Government-issued information leaflets sent to every household in the UK had Switchboard's number printed on them - and demand for the helpline soared.
Switchboard became a vital source of information to help people avoid HIV transmission.
But this did not stop the virus from ripping through the gay community, with tragic consequences.
Looking at a photo taken at a gay pub in Islington in 1984, Lisa says: "It's very poignant as a shot of the brightest and best of the London lesbian and gay movement, as HIV was only just beginning to hit us.
"All that sunshine, all those hopes. And a total lottery of who got through."
Diana James describes this era as being "a heartbreaking but also fantastic time to be LGBT".
The 60-year-old, who lives in Cornwall, became Switchboard's first transgender volunteer when she joined in 1988.
It was the same year Margaret Thatcher's government introduced the hugely controversial policy, nicknamed Section 28, to stop the "promotion" of homosexuality.
Standing inside a tiny office above Housmans bookshop in King's Cross, from where she used to sit and answer phones, Diana remembers the homophobic prejudice she and her colleagues would face.
"We used to have a little hole cut in the door so you could see outside to see if there was anyone waiting for you when you left," she says.
"It was a tough time. There was all sorts of right-wing groups that thought kicking a queer was a good way to spend an evening after a few beers."
For Diana, the prejudice didn't always come from straight people.
At that time the helpline was called London Lesbian and Gay Switchboard (having rebranded from Gay Switchboard in 1986), and some volunteers felt hostile to the idea of bisexual or trans people answering the phones - even though many callers identified as bisexual or trans themselves.
Lisa Power had argued vigorously for Diana's recruitment, and she was only accepted on to the team because she was a lesbian, not because she was trans.
"There was a lot of protest and a lot of upset. People left [because of me joining]," Diana says.
"This was at a time when trans issues were not understood. Sex and sexuality were still very much mixed, in not only the average straight person's mind, but those of the gay community as well.
"But as a dyke, I wanted to help people. And it was also the kudos of being a Switchboard volunteer - I really wanted to do it," she says.
Homophobic legislation, right-wing thugs and fear of Aids might feel like ancient history to young LGBT people today.
But many of the issues of the 1970s and 80s are still prevalent.
Ki Hng, a microscope technician at UCL, believes she helps other volunteers to understand that many LGBT people still struggle to come out to their families.
"Because I'm bisexual and I grew up in Malaysia, which is a very conservative, heteronormative country, I assumed I was straight," Ki explains.
"Even though I had crushes on girls, I didn't have the vocabulary and I didn't identify it. I didn't know that was even possible."
After Ki broke up with her long-term boyfriend and moved to London in 2011, her mother accused her of "liking girls".
"She started trying to exorcise me," Ki says.
"She's a fundamentalist evangelical Christian American type, and started saying things like 'In Jesus's name I cast this demon out from you' and that sort of thing, which was both terrifying and upsetting... but also a little bit comical because it was over MSN messenger."
Ki hopes that she can draw from her "horrendous" coming out story to help people she speaks to on the phone as a Switchboard volunteer.
"My experience does help me to be more empathic, to be more understanding," she says.
"I believe I bring something to Switchboard that is still currently a bit underrepresented, so people who are more ethnic or have more exposure to religion, and the difference of reactions from parents."
Tash Walker, Switchboard's current co-chair, has been studying archived notes about calls to the helpline.
She's noticed people feeling isolated and unable to come out to their loved ones has been a common conversation throughout Switchboard's history.
It's therefore perhaps unsurprising that one in three LGBT teens in England has a mental illness, while homophobic and transgender hate crime have both risen in the past few years.
"Mental health in the LGBT+ communities is very much lacking in support," Tash says.
"Switchboard is still needed today. The fact that we're still here 45 years later, we're getting around 15,000 calls a year... it speaks for itself."