You’ll find them in boardrooms, classrooms and courtrooms ... when they’re not swapping partners in strangers’ bedrooms.

It is surprisingly simple to find a swinger in Perth. Perhaps the bigger shock is where they spend the rest of their time.

They are teachers, lawyers, nurses and directors, and when they are not attending sex parties at clubs, on boats or at houses in the Kalamunda hills, they’re running businesses, book clubs and organising play dates for their kids.

Take for instance Ben, 46, and Bronwyn, 40, (not their real names) who met with The Sunday Times at a CBD coffee shop less than two minutes from where they both work as project managers for leading IT and mining firms.

Neither would garner a second glance at a barbecue or a conference table, and yet for two years they have been carrying around a secret that most would baulk at: they regularly have sex with husbands and wives that aren’t their own.

Four years ago the couple’s marriage was on the rocks, thanks in no small part to a sex life driven to the edge of extinction after being forced into a lopsided time-share with the competing demands of three young sons and draining full-time careers.

Then, at Ben’s suggestion, they began exploring “consensual non-monogamy” — swingers’ talk for their lifestyle.

“When he broached it initially, I was flabbergasted,” Bronwyn said.

“My outlook at that point was very black and white.

“It means you don’t love me, it means you are not here in this marriage with me — you get the picture.

“I was expecting it to be seedy and dark and dingy, and full on. That you’d walk in the front door and drop your clothes and everyone would just be going for it.

“But it’s not like that at all. It is a normal dinner party or a barbecue. And then suddenly it changes.

“But there is no one that goes ‘OK here’s the bowl, give me your keys.’

For Jason and Vicky (also pseudonyms), an engineer and a relief teacher, swinging began as a way for Vicky to explore her bisexuality.

The married couple, both 30, had never had sex with anyone but each other, until a chance sexual encounter between Vicky and a female friend — with Jason’s blessing — opened the door to swinging.

“After a lot of talking and researching we just bit the bullet and went to a local swingers’ club,” Jason said. “We were very nervous and we didn’t think we would play, but very late in the night just before they closed we ended up in a room with another couple.”

For both couples, one of the biggest surprises was the calibre of company they soon found themselves enjoying at parties and sex clubs all over Perth.

“Honestly, I thought it would be the sexual deviants of the world and, it sounds awful, but lower-class people, people obsessed with sex with nothing else in their lives,” Bronwyn said.

Ben said: “Because swinging is not out there and a societal norm, you see it as one of those underbelly things. I would describe it as underground, but not underbelly.”

In truth, even underground may be a bit of a stretch.

The biggest Australian website connecting swingers with like-minded couples contains tens of thousands of active profiles and was conceived here in Perth, which remains the nation’s capital of cross-marriage copulation.

“The scene is surprisingly big in Perth,” Ben said.

“You get every shape, every size, every age, every colour, every creed.

“Predominantly we find between the age range of 35-55 is the sweet spot, that is probably 70 per cent of the people out there.

“And professionals. A lot of business owners, teachers, nurses, lawyers, financial advisers, people in politics. Not actual politicians, but certainly people on their staff.

“On any weekend there is probably a choice of two clubs and a party, or two parties, to go to, and the clubs are generally open Thursday, Friday and Saturday.”

One such venue, Infusions in Belmont, was last night charging couples $70 to attend one of its regularly scheduled Swinging Saturday events. Single women — something of a rarity in swinging circles, especially so-called “unicorns” who are up for sex with individual men, women and couples — only need shell out $20.

“Dressing down into lingerie or boxers is encouraged. When choosing your outfit ... think sexy,” the event description reads, going on to detail the “seductive, fun, purpose-built venue” as containing “four play areas, including a private room and two massive luxury group areas”.

A sex swing, dance pole, towels, lube and condoms are all provided.

For those who prefer a higher level of discretion, exclusive invitation-only soirées occur regularly across the city.

On New Year’s Eve Jason and Vicky joined about 70 other couples at a private home north of the river for a “red carpet Hollywood” themed event.

“They had basically stripped everything out of the house, put extra beds in and got rid of any furniture that might get wrecked,” Jason said.

“Then they had a couple of spas out the back and massage demonstrations and all sorts of stuff.”

For the uninitiated, or “vanillas”, the details are confronting.

But a podcast dedicated to the lifestyle in Australia that is downloaded more than 4000 times a week, Swinging Down Under, demonstrates just how widespread it has become.

Its married founders Cee, 34, and Dee, 43, began swinging in Sydney in 2014, but have since moved to Singapore where they both work as regional directors. They regularly return to Australia, and Perth, to host events and parties attended by scores of couples.

“Our generation is different to our parents’ generation and this whole idea of ‘Gee I better get married at 18 and get a home with a picket fence and a couple of kids’ has decreased,” Cee said.

“Nowadays, some people are choosing to concentrate on their careers or choosing to have children later, or not at all. We are questioning what we want our lives to look like and not just our careers, but also love and sex.”

A big part of the reason they started Swinging Down Under was to combat the rampant negative connotations that abound about the lifestyle.

“You know the old keys in the bowl bull---t,” Cee said.

“There is a misconception that this is bored couples or old seedy guys in gold chains with way too much hair growing out of their chest, but that is not what happens these days at all. The people you meet are well educated, live very balanced lives and are successful through all walks of life.

“There are some people that want to hit and quit, have sex with another couple with no names taken and just go and have a great time.

“For us, we prefer to classify as more social sexual.

“We want intellect and sense of humour, as well as physical attraction and more of a pants on/pants off friendship.”

Back in Perth, Ben and Bronwyn have a similar approach, meeting new couples either online or at one of the city’s three main swingers’ clubs, but regularly going back to those they form a connection with.

“We’ve got great friends now and maybe play once out of every four or five times we see them,” Bronwyn said. “But other times we’ll meet up for lunch with our kids and their kids.

“It’s so normal, it’s not dirty — we are just friends and every now and then we’ll all have sex and it’s like ‘Well that was nice, do you want a beer?’”

They also maintain strict rules and boundaries, and caution that swinging is certainly not for everyone.

“We have been to house parties where new couples come along — usually it is the husband’s idea — and at the beginning they are both tentative, but by the end of the evening the wife is all over it with two other guys and the husband is fuming and just wants to get out of there,” Ben said.

Jealousy is an unavoidable and constant companion for swingers, although it stems not from the sexual acts, but rather from intimacy, the separation of which lies at the heart of what appeals to couples like Ben and Bronwyn.

“(The jealousy) is not about them being with someone else, it’s more like ‘I didn’t like the way you looked at them afterwards’ or simple things like kissing — that is our thing,” Bronwyn said.

Vicky and Jason believe humans did not evolve to be monogamous, and said they felt the perceptions around swinging were slowly changing.

“Half of marriages fail and in many of those cases, one or both will go and cheat on their spouse,” Jason said.

“We’ve heard a lot of stories from friends in an office environment where someone finds out they are swingers and people immediately assume there must be something wrong with them or their relationship.

“Whereas you go and tell those same people you are cheating on your wife and that is somehow more socially acceptable. I don’t understand it.”