Those keen to enjoy the freedom of baring all are feeling beleaguered, finds William Langley.
They are baring all on the beaches, stripping off in the shires and going starkers in the suburbs. This month, Britain's legions of naturists mark an important anniversary, but overshadowing the celebrations is an ominous new mood of suspicion and prudery.
Not only dedicated "lifestyle" nudists but also those who merely fancy an all-over tan or a spot of skinny dipping are experiencing a toughened response from the authorities. Last week in Northern Ireland, two men who wandered naked out of the sea near Belfast were threatened with prosecution and being placed on the sex offenders' register. The police said online that skinny dipping was "NOT a good idea", and warned: "We are treating this kind of behaviour extremely seriously, and will be continuing to take action against anyone who decides to do the same."
According to Malcolm Boura, the outraged campaigns director of British Naturism (BN), such heavy-handedness is becoming increasingly common. He mentions that "there was a chap not long ago who was walking through Sherwood Forest. He spotted someone riding a horse in the distance and decided to cover up, but the next thing he knew there was a police helicopter overhead, and a whole squad of them coming out of the trees, threatening to do him for indecent exposure.
"It's not just completely over the top, it's a display of ignorance," Mr Boura continues. "There is no law against being naked in public, but too often the police simply don't know that. So you get people being threatened with arrest even for taking their clothes off in their own gardens. Then, when the authorities find that no offence has been committed, they think of something else to charge you with - like causing a public nuisance - and even if you are cleared, you end up with a big legal bill."
His organisation is deploying the term "gymnophobia" - an irrational fear of nudity - to describe what it feels it is up against, although Mr Boura can also put things more plainly. "Our members are bloody furious," he says.
BN - formed from a merger of the quaintly named British Sunbathing Association and the Federation of British Sun Clubs - turns 50 this month, at an apparent crossroads. While displays of the flesh have never been less escapable - largely thanks to the internet - a strain of neo-puritanism, compounded by other complex factors, is gnawing at nudity's popularity.
Some social scientists argue that our celebrity-driven obsession with body image and, conversely, the growth of obesity have made us less willing to go naked. Others say the "paedophile frenzy" resulting from cases such as those of Jimmy Savile and Rolf Harris is a disincentive, particularly to men, to be naked in public.
Membership of BN has fallen sharply over the past 10 years to around 10,000, although the organisation's research suggests that more of us are embracing the informal naked option than ever before. If so, Britons are going against the global grain.
The latest issue of French Elle carries the cover headline "La Fin du Topless Sur la Plage?", with a report on the reluctance of today's Frenchwomen to bare their breasts on the beach. This amounts to a seismic reversal for a country that - largely thanks to the good offices of Brigitte Bardot and the chic Saint-Tropez set of the 1960s - not only popularised topless sunbathing, but also helped set the sexual revolution rolling.
Elle suggests that the retreat is partly down to health concerns, with greater awareness of skin cancer risks, and partly to the unseemly politicisation of breasts by militant organisations such as Femen and Free the Nipple, an American group fronted, so to speak, by Scout Willis, daughter of the Hollywood star Bruce, which claims the US is waging "an insane war against boobs".
Some see a further reason in the sorry legacy of those '60s breast-barers. Bardot, 79, now denounces Saint-Tropez. "It's a strobe-lit, rock-blasted place of indecency, exhibitionism, vice and greed," she told me. Modesty, goes the argument, feeds decorum, and results in a nicer resort. Today, according to Elle, only 2 per cent of Frenchwomen under 35 say they would go topless.
Germans, as anyone who has wandered through a public park on a hot afternoon in their country will know, tend to have fewer inhibitions than most about stripping off. Yet even in the home of Freikörperkultur - free body culture - the new prudery is creeping in. Kurt Fischer, president of the German Federation of Nudist Clubs, says the numbers going naked are in steady decline.
Some blame the country's changing demographics, with large-scale Muslim immigration bringing an edge of social and religious conservatism to a society that once barely raised an eyebrow at nudity. Unclad sunbathers have reported being abused and threatened by passers-by, and some municipalities have recently cordoned off areas where nudity is permitted. Younger Germans, moreover, appear less ready to peel off than their parents, with polls suggesting that most under-25s prefer to stay covered.
The US and Asia, for their part, have never truly caught the nakedness bug, and show few signs of doing so (with the honourable exception of Joe Biden, the vice-president who, according to reports from secret-service agents, has a penchant for skinny dipping). Only a handful of public beaches in America permit topless, let alone nude, bathing. Meanwhile, a survey by the travel company Expedia, published last month, suggests that a mere 2 per cent of Japanese women and 3 per cent of South Koreans have gone nude (compared with 28 per cent of Germans). In China, a stern tradition of Confucian rectitude makes public nudity unacceptable, and even in the few naturist centres that exist, the sexes tend to be segregated.
So why should going naked be such a big deal? Historians disagree on when humans first started wearing clothes - 100,000 years ago seems a reasonable guess - but broadly concur that, for 99 per cent of our time on Earth, nudity has been the norm, and that dressing for the sake of decency is an almost wholly modern phenomenon. In the West, it wasn't until the early Christian moralists began to make an association between nudity and sin that the big cover-up began. "The naked body," wrote the art historian and author Kenneth Clark, "ceased to be a mirror of divine perfection and became, instead, an object of humiliation."
Once established, the obligation to wear clothes has proved fiendishly hard to overthrow. While Britain has no specific offence of public nudity, a prosecution can be brought on the basis of an intention to cause "distress, alarm or outrage". For all that, the supposedly squeamish British have shown the world the way to display.
The world's first naturist club was founded by Charles Crawford, a British circuit judge serving in Bombay under the Raj, in 1891. Faithful to its motto Vincat Natura (Let Nature Win), the club required its members to be stark naked at all times, with exceptions made only for wedding rings and false teeth. At the start of the 20th century, the Germans briefly took over the running with the publication of a celebrated series of philosophical papers on the benefits of nudity written by the social reformer Dr Heinrich Pudor. However, the rise of the Nazis drove the practice underground, while Britain's naturist clubs flourished, leading to the launch in 1932 of Health & Efficiency, the world's first naturist magazine.
Today, BN employs a parliamentary adviser, a commercial manager and a media consultant. It oversees the activities of more than 70 individual clubs, and says the activity has never been more popular. To its core devotees, the appeal remains just what it always was - the heady sense of freedom, innocence and oneness with nature.
They suspect that such feelings are not shared by the new prudes patrolling our woodland paths and foreshores for an incriminating glimpse of uncovered flesh. Fifty years ago, when naturism seemed to have soared into the modern era, it was assumed that such provincialism would be left behind - but the anniversary finds our beleaguered naturists short not only of clothes, but also of hope.
The Telegraph, London