Justine Drury did not want to upset the fishers, but her customers wanted to swim naked.

“And if that’s what the people of Nottingham city want – if that’s their way of connecting with nature – then who am I to stand in their way?” said the co-owner of the WholeHealth swimming club. “But we did have to think of the fishermen. They are quite old school.”

Accordingly, the first ever skinny dip at Colwick Lake last year was held before the fishers arrived for the day. The 5.30am event was, said Drury, awash with enthusiastic naturists.

“We’re now thinking of having an event every month,” said Drury, a former headteacher. “We held the first event because we’re a socially responsive company, but we’re going to make it a regular thing because it makes good business sense; when we hold these skinny dips, we’re inundated.”

Mainstream companies are increasingly realising that catering to the “buff pound” makes sound business sense. Andrew Welch, from British Naturism, said venues now regularly hold their own naturist events after having hosted a one-off occasion with his organisation.

“The buff pound is definitely something that businesses are increasingly aware of,” said Welch, who is busy organising this weekend’s annual Great British Skinny Dip.

“They hold one event alongside us and then realise it’s a great commercial opportunity: if they put on something a bit unusual at a time of the week when they wouldn’t usually be open or have many customers, they get a guaranteed crowd.”

Rachel Weick, of Bare West Events, agreed. “Most venues want a slice of the action once they’ve seen events in the flesh – excuse the pun,” she said. “If, for example, you’ve got a lovely garden, then it’s a no-brainer; people want to get their clothes off in a nice garden, almost irrespective of the weather – and if the hosts provide a cream tea, a barbecue or a bar, they’re guaranteed good business all night as naturists aren’t going to go off site because they want to be naked.”

This weekend, the UK’s biggest naturist event, Nudefest, returns to the West Country with naked karaoke and slip’n’slide. It comes just weeks after thousands of people joined the World Naked Bike Ride – an event that has taken place annually in 200 cities across the globe since 2004 – while next month, Nothing On Events will hold a Garden of Wellness festival in West Sussex as part of its summer schedule.

Arundel Lido in West Sussex is about to start holding monthly sessions after the success of its first tentative event. “We held our first naturist event just to see what the uptake would be, and were stunned when 80 people turned up,” said Nikki Richardson, its general manager.

“It makes perfect business sense because we’re reaching a whole new client base; naturists are prepared to travel for miles – we had people from the Isle of Wight and from Portsmouth.”

Briony Newsome, the acting chair of the Shap open-air swimming pool committee in Cumbria, decided to warn neighbours whose houses overlook the pool when they started holding their regular monthly sessions recently.

“But we got absolutely no complaints at all,” she said. “I think locals are aware that these events bring new business into the village as a whole. Because naturists tend to come from so far away, they spend the whole day here.

“We’re wondering if it might be a new string to our bow too,” she mused. “I think naturist families who come to our events might well decide to hire the pool out privately at another time for naturist sessions just for themselves and their similarly minded friends.”

Johnny Nicol, the owner of Race Hub, an open-water swimming venue outside Leicester, held his first “clothing optional” event as part of British Naturism’s Great British Skinny Dip last year and has never looked back.

“We’re thinking of making it a monthly event now, from June to September,” he said. “It’s a great business opportunity: because there aren’t many naturism events, you’re guaranteed lots more people coming than we might usually attract.

“But you’re also going to benefit from the publicity it generates at other times too. Mainstream attitudes to naturism are pretty relaxed now. Even if people aren’t into it themselves, they’re sympathetic to it. We reckon non-naturists will hear about these events and will think of coming to the lido at regular times themselves.”

But the cost of living means other venues are struggling to keep their naturist events going. Elaine Hudson, the manager of Wigton Baths in Cumbria, said it would have to curtail its naturism sessions from two hours to one.

“It’s very sad,” she said. “We’ve only just started having these regular sessions and they’re very popular, but there are two issues: it costs us almost twice as much to heat the pool than previously – and because petrol costs have increased so much, the number of naturists coming from further afield has almost halved.

“We were making a good profit from the sessions last year, but now people are clearly thinking: ‘Do I go for a nice naked swim or do I stay home?’

“Sadly, they’re opting for the latter. And that, combined with the increased cost of heating the pool, means we just can’t carry on.”

The bare facts about naturism

• It is legal to be a naturist. Naturists have a legal right to freedom of expression which only engages criminal law if they commit sexual offences or use disorderly behaviour that they intend to or are aware may be disorderly within the hearing or sight of a person likely to be caused harassment, alarm or distress.

• An Ipsos Mori poll in 2011 found that 6% of people in the UK considered themselves to be naturists: almost one person in 17, or about 3.7 million people. In 2001 the percentage of naturists had been 2%.

• More than 15,000 people attended organised naturist events across the country last year,

• The 9,000-strong membership of British Naturism grew over lockdown by about 2.5%: by mid-March 2020, it had 180 new members, and by the end of May, 500. Since the beginning of 2022, 600 more people have joined.

• There are more than 100 naturist clubs and swims across UK. Clubs offer naked dining, boat trips, bike rides, art gallery visits, museum visits and sports. “Our walks are particularly popular,” said Andrew Welch from British Naturism. “Clothed people coming in the opposite direction find it funny or intriguing. They’re never offended.”

• One key piece of etiquette: “If it’s bad behaviour with your clothes on, it’s going to be bad behaviour with your clothes off. But we do always sit on a towel,” said Welch.