In a darkened and sweltering room in Hackney, dozens of people are dancing to pounding 50s rockabilly. The men are in braces and cravats; the women in sparkling dresses and pork pie hats. Most are supping booze served in flutes. All cheer when a compère – dressed in a bow tie, shirt and hot pants – climbs on stage and introduces a flapper girl group. So far, so East London.

There are, however, perhaps two slight differences between this and your average night out in scenester-land. Firstly, it’s only 2PM. Secondly, all 120 revellers here are at least 60-years-old, and often considerably older. Welcome to The Posh Club, an outrageous weekly cabaret-style party for people who – like the crockery the afternoon tea is served on – are of a certain vintage.

“When I first started performing here,” says Elvis impersonator Conrad Hamilton, “I thought, ‘OAPs, relaxed gig, no problem’. I could not have been more wrong. It’s the only place I’ve ever had knickers thrown at me.” There’s a pause of recollection. “They were big granny’s bloomers,” he says.

The Posh Club, it has been joked, puts the disjointed hip in hipster. There are literally crutches and walking sticks left by the dance floor. They once had to call an ambulance here because a woman in her 80s was having so much fun she forgot to take her daily medication.

“We’re probably the only club event in the world,” says producer Dicky Eaton, “where someone was rushed to hospital because they’d forgotten to take their drugs.” The oldest reveller, he adds, is 108. “Although, we haven’t seen her in a while…” Neither of us decide to dwell on why she might have stopped coming.

In any case, the point is that this event – one of five such regular pensioner shindigs run by London’s legendary alt club promoters, Duckie – is doing something truly unique: reinventing the idea of an older person’s social by refusing to do gentle and well-behaved. Here, live music, champagne and innuendo are the order of the day. All for a fiver a head.

“It’s probably the most rewarding thing I’ve ever been involved with,” says Dicky, who has worked with Duckie since it first threw gay nights at London’s Royal Vauxhall Tavern in 1995. “What we’re doing is really an anti-loneliness campaign presented as a club event. A lot of our guests maybe don’t get out as much as they once did and don’t see friends as often. Well, this provides a unique way to do both, while also being part of something that’s vibrant and exciting. Just because you reach a certain age, doesn’t mean you don’t want to have fun anymore. I think society has a habit of forgetting that. A lot of what we, as younger people, do to enjoy ourselves, these guys, they’ve not only seen it and done it all, they invented most of it.”

Everyone here is dressed to impress. Cuban heels, statement jewellery, capes and top hats can all be seen. I speak to 84-year-old Joan Huxtable. Friends call her Pinkie, because of her hair colour. “If a teenager can dye hers,” she demands to know, “why shouldn’t I?”

Today’s event kicks off with afternoon tea silver-served by some 20 volunteers in waistcoats; warms up with a flapper girl performance while the champers is poured; and gets steadily rowdier as things progress. There are no naked ballerina or burlesque performers stripping to nipple tassels (as there have been previously), but when Hamilton – whose hip thrusts are met with insatiable wolf-whistling – says he’s too hot on stage, he gets booed for only removing a tie. On the dance floor, the hip-swaying begins to border on twerking.

“My mum was still dancing until she was 91,” says 74-years-old Mabelyn Dick. “I want to beat that – come back in 17 years and I hope I’ll still be here.” She is wearing face paint. “It’s about staying glamorous,” she tells me.

Another guest drags me outside. Her name is Margareta Warllin and she’s 80-years-old. “It’s too loud to hear yourself think in there,” she says as the door closes on "Twist & Shout". “Isn’t that marvellous? Isn’t that just how it should be?”

The whole thing is the brainchild of Duckie founders Simon Casson and sister Annie Bowden. Their mum moved from Hackney to Crawley seven years ago and, aged 80, found herself feeling lonely. To cheer her up, the two siblings threw a vintage tea party in her front room. They invited a couple of neighbours – both in their 90s – served up sandwiches and scones on specially bought crockery and played 1940s records on an old gramophone.

The three ladies loved it so much, Simon and Annie decided they’d do it again. But this time in a local church hall, and with invites being sent out to older people across the area. They decorated the place, got a few more second-hand records, roped in some friends to act as waiters and, using their connections to London’s alternative nightlife, brought in a couple of turns to provide entertainment. “That went so well,” says Dickie, “that the Posh Club was born.”

It’s been running in Crawley more or less ever since, while also expanding to Hackney, Elephant and Castle, Hastings and Brighton. Tight funding (it’s run as a social enterprise subsidised by grants) means it’s not continuous in all five locations. In Hackney, for instance – where it takes place at St Paul’s Church Hall in Stoke Newington Road – they have two seasons of 10 weeks every year. Nonetheless, it’s estimated more than 10,000 revellers are served by 200 volunteers across the quintet of clubs every 12 months.

“We’d like to open more,” says Dickie. “We get people coming here from other cities while visiting friends or relatives in Hackney, and they always say, ‘Why can’t we have something like this where we live?’ So that’s an ambition. But it would need to be quality, have the right atmosphere, be done with love – because if it doesn’t have those things it’s not The Posh Club.”

One man who would support the expansion is Father Niall Weir, the rector of St Paul’s. Getting into the spirit of things, today, he gets on stage – dog collar and drink – and, during a brief speech which is ultimately about love and companionship, finds himself admitting: “I was a bit of a go-er in my youth.”

“Should a man of the cloth be admitting such things?” I ask him later on.

“Why not? It’s all good fun,” he says. “One of the biggest challenges we face is the isolation of older people. The Posh Club tackles that superbly. It gives its guests everything that is needed for human contentment: connection, laughter, physical activity. The implications it has on improving health and well-being are extraordinary.”