The parties are hugely opulent, a recent one having taken place in a �30 million house in Marylebone.

London - Guests wander the luxury Mayfair apartment in formal attire, chit-chatting, lounging on sofas and sipping champagne.

At midnight a bell is rung and everyone gets naked.

Around half an hour later, after the initial awkwardness has worn off, the flat is a sea of writhing bodies.

Heaven Circle, probably the world’s biggest sex party club (it’s the one from a Channel 4 doc titled Sex Party Secrets), started out in 2012 as founder Chris Reynolds Gordon and just a handful of friends. Four years later, it has over 20 000 members, with parties taking place in London, Paris, New York, L.A., Vegas, Ibiza, Berlin, Amsterdam and Vienna.

They always sell out.

The parties are hugely opulent, a recent one having taken place in a £30-million house in Marylebone. “How do you find the venues?” I ask Gordon. “I live in them,” he tells me, which demonstrates pretty well how lucrative a business it is and the enormity of the world’s sexual appetite.

“If you’re going to have sex with a total stranger, you’re probably going to want them to be attractive, so Heaven Circle vets its guests, even operating a tiering system with extra special parties for the sexual elite.”

“A ‘sex olympics’ is currently being planned, where the best performers from parties around the world will come together for a sort of fantasy team orgy. The mix at the parties tends to be mostly swinging couples, with a few men and women thrown in too.

While the prospect of having so many sexual encounters in one go might frighten some, the organisers believe the parties to be safer than clubs.

While the latter are plagued with unwanted gropes, the former is a less ambiguous environment. Everyone knows why they’re there.

Consent is also held in paramount importance, with undercover bodyguards at all parties (wearing Y-fronts and bow ties, the best kind of disguise).

“I go to some of the best clubs in London and I find my parties are just friendlier,” Gordon says. “I mean, if you’re about to f*** someone’s wife, you’ve got to be pretty friendly.

“In a normal club people are often a bit hostile, show off why, they like to keep themselves to themselves. There’s not that kind of ‘Hey, how are you?’ – just randomly chatting to people – that we have.

While Heaven Circle is a secret indulgence for most members, it seems that in an increasingly sex positive age where dating and hook-up apps like Tinder are ubiquitous, this embarrassment is fast eroding.

“Seventy or eighty percent of our members use photos of their face,” Gordon explains.

“You would never have got that before. It used to be pictures of, like, an arse bending over, now their photos are all them. They don’t give a f*** - even in the workplace, people will say ‘yeah I went to an orgy’ and the response will be ‘ah, cool.’

“It’s not even taboo anymore,” he adds.

“I remember about 10 years ago when Plenty Of Fish came out people wouldn’t want to talk about it, they felt only ‘weird’ people go on those kinds of services. Now it’s so mainstream, people are screen-shotting Tinder and showing their friends.”

The company’s next step is Heaven Prive, which will see it facilitate members setting up their own parties, potentially creating an explosion of orgies in countless other towns and cities.

“It’s evolving in a very, very short period of time,” Gordon says.

“I believe that in 20 years time this will be extremely normal, it’s on a crest of a wave at the moment and I’m just fortunate I got there first.”

The Independent