The room smells of smoke and sex. The excitable, scruffy boys, cradling glasses of bootleg vodka, are primed like cocked pistols. The girls let cigarettes linger on their lips and eye their targets. Their hair falls around their uncovered shoulders and they wear minidresses, or tight denim and strapless tops – outfits that are not so much suggestive as declamatory. Here is a woman, they say.

We are at a party on the top floor of a concrete residential block in Tehran. It’s a vast, open-plan apartment, like many in the affluent north and centre of the city. “Perfect for entertaining,” the Foxtons salesman would say, but he wouldn’t know the half of it.

There are 40 guests here, all in their twenties. Everyone knows everyone. You would never invite a strange, someone no one could vouch for, to this. They catch their breath and gossip around the olive-laden dining table, but the action is in the living room, where a pop-up night club has emerged. The bar serves whiskey and vodka, bought from Armenia “dealers”, who – being Christian – are allowed to alcohol, and decanted into Jack Daniels and Absolut bottles.

The hosts, two good-looking male students who share this place with their (liberal, and out-of-town) aunt, take turns to DJ. They play Persian hip-hop, which like its American counterpart, focuses on fast girls and pretty cars. It does the trick. In front of the sound system, the partygoers grind and twirl against each other. Some will pair off by the end of the evening. Others – including a young gay couple with their hands all over each other – already have.

© Alamy

We are in Iran, but not the one you see on television. That Iran - the cartoon villain – is a country of mullahs and chuddars, of angry protesters brandishing “Down With America” placards. It is a country ruled over by the hyper-conservative Ayatollah Khamenei and administered by the American-baiting, anti-Semite President Mahmoud Ahmadinejad, a man with the wardrobe ad the politics of a mini-cab driver.

Of course, that place exists too. And, while its exclusive hold over the Western imagination is an insult to the kindness and sociability of most Iranians, its strictures are only too real. Iran is a country governed by Sharia law and, where alcohol is banned for Muslims, and contact between unmarried women and men is forbidden. Indeed, women – despite graduating from universities in greater numbers than men – are, literally, second-class citizens. They have inferior divorce rights, and their legal testimony is only worth half a man’s. Meanwhile rape, murder, drug trafficking and homosexuality are all punishable by death. Iran executed at least 346 people in 2008, including eight children, and still considers stoning a legitimate punishment.

Ever since the revolution of 1979, when the Shah’s Westernised regime was crushed in a popular uprising, Iran has been ruled – some would say hijacked – by religious hierarchy in which the Ayatollah has ultimate power, and anti-Islamic politics is not permitted. Thirty years on, Ian’s political structure is a confusing medley of autocratic and democratic systems. A Guardian Council of religious figures is subordinate to Ayatollah Khamenei, while the democratically elected president leads the government.

The balance of political power is delicate. Under President Khatami, the last reformist before Ahmadinejad, Iran’s laws, particularly on morality and censorship, were relaxed. But even a reformist cannot change the fundamentals of a political system – a system that was described to me as “the guy with the beard calling the shots”.

We are in Iran, but not the one you see on television

Under Ahmadinejad, a staunch conservative and Mahdist – the equivalent of a born-again Muslim – who became president in 2005, there has been a fresh crackdown on journalists and dissident figures, while Iran’s reputation abroad has been muddied by the president’s frequent provocations. While I was in Tehran this year, the Iranian-American journalist Roxana Saberi was convicted and jailed for eight years for espionage in a closed trial that lasted a day. She has since been released after her punishment was reduced to a two-year sentence. Meanwhile Ahmadinejad did his utmost to scupper President Obama’s overtures at diplomacy by mocking Israel as “a racist country”. The local, pro-government press called his xenophobic speech “the last bullet in the brain for the West”.

On 12 June, Iran will go to the polls to choose a president They may again choose Ahmadinejad. Despite (and because of) his entrenched positions, in particular his unwillingness to back down on Iran’s nuclear quest, he is still popular, particularly with the poor, conservative majority. But his country is failing. Inflation runs at around 25 per cent and jobs are scarce, while the president’s own pronouncements have become increasingly schizoid. The credible alternatives, two religious men of a more liberal persuasion – Mir-Hossein Mousavi and Mehdi Karroubi – stand a chance.

The other Iran, which co-mingles with this official version is, like the bottom of the iceberg, barely visible, and rarely discussed. But, it is there. Two thirds of Iranians are under 30 years old, a product of the huge loss of life in the Iran-Iraq war of the Eighties and the subsequent baby boom. And, while many of this generation have left (every year 150,000 relocate to American, Britain, Australia and Canada), a significant number have stayed.

Now, a minority of the most daring young people – steeped in Western influences through travel, satellite TV and the internet – have created a home-grown scene that is wild, addicted and constricted to the inside of each other’s homes. In public, they play ball with the Islamic regime. In private, they just play.

© Rex/Shutterstock

The scene’s ground central is Tehran – a city of gorgeous people and joyless concrete architecture; of suicidal taxi drivers and huge murals depicting the Ayatollahs – which rises from the impoverished south to the affluent foothills of the Alborz mountains in the north. In the capital city, this other Iran flourishes, despite the activities of the state thugs, the basiji, who break up any kind of anti-government activity, and the gasht ershad, the morality police who roam the streets upbraiding and arresting those who dress and behave in ways they do not care for.

The young of Tehran have adapted. While they test laws, they do not flout them outrageously. When they are arrested many will tell you that they deal with inconvenience as they would flies at a picnic. But their masks a sense of unease. Mehdi, the lean, friendly, 22 year-old host at the top-floor party, says he stopped counting when had been arrested 20 times.

Mehdi is of a generation which takes it values not from the mullahs, but from the film-makers, artists, musicians, students and hipsters in their twenties and thirties. Together, they are rewriting the rule book. Dinners and parties where alcohol is served, where girls leave their hijab at the door, where drugs are available, where sexual appetite thickens the air, are common. And there is little the Islamic Republic can do to stop it.

On a Thursday night – the equivalent of a Saturday night in Britain – Golsa, a pretty garrulous young film director takes me uptown to a party. She was born in the notorious Evin prison in 1983, where her parents were jailed for their political activities, and lived in London during her teenage years. Like many of the 25-30 generation who grew up during the Iraqi bombing of Tehran, she’s fiercely opinionated.

The scene’s ground central is Tehran – a city of gorgeous people and joyless concrete architecture

Watch Golsa for a day or two, and you get a sense of how exhausting life is for independent young women here, of how many masks they must have to wear. She meets me in the evening in a colourful (and hence provocative) outfit: a bright orange Kurdish headscarf, and a blue and white ankle-length skirt. But, before we visit a public building she is forced to go home and change into her black maqnae, a “half-chuddar”, which she complains, “other girks can look realy good in, but it doesn’t suit me at all”.

The next day she is back in a bright blue scarf, when, on a shopping trip in Vanak Square in the fashionable north, she freezes. She’s seen the morality police, and tells me to cross the road with her to avoid them.

“It’s not that anything too bad will happen to me,” she says, “but they’ll tell me off for something, and then they’ll start asking me questions about you…”

Later that evening, Golsa is wearing lipstick and hiding a strappy top beneath her coat. And, by the time we’re inside the apartment of her film-making friend, Arash – a place decked out in an oak bar and an enormous flat-screen, like a hedge funder’s bachelor pad – she has already stripped off so that her shoulders are bare. It is, I realise, the first time in two days that I have seen her hair.

Over the evening drinks, Golsa tells me her worries for the elections. She says, “Most of the younger people won’t vote, all they want to do is party”. Arash, who, at 30 remembers the relative freedoms of the Khatami period, agrees. Between making vodka cocktails from a drinks cabinet that would put a brigadier to shame, he says, “I don’t know about anyone else, but I will be voting. We are like ants. One ant is no use. But a million ants…”

© Alamy

Tonight, we are heading to a party at the house of a rich son of a former diplomat, but on the way, we pass along Iranzamin, a famous road in north Tehran where teenagers come to flirt. At first, I can’t see any action and then I see it’s all around me. Pairs of girls, mostly with blonde fringes and headscarves thrown back so far they might as well have been left at home, drive cars with the windows down. The boys are doing the same. They chat to each other out of the driver’s window, before numbers are exchanged.

The girls are “duffs”- a half-derisory term, half-admiring term for the Paris Hilton clones who congregate in the coffee houses and shops of north Tehran. (At the bazaars, you can buy cheap, knock-off fashion, imported under dubious circumstances, or you can go to the malls, where bona fide Hermès, Gucci and Cavalli compete with lingerie shops. Laughably, the morality police wait at the door to catch women with their headscarves down – as if it matters what you wear while you’re picking out a thong and a miniskirt.)

Like other young Tehran women, the duffs adapt their hijab into the tightest, sexiest outfit they can get away with, but go the extra mile with a shock of peroxide blonde hair. Many (and, weirdly, a lot of middle-aged men) sport plasters on their noses. This is a badge of honour. Tehran might just be the nose job capital of the world – 90,000 noses are fixed in Iran every year, most of them in the capital.

At 10pm, we are buzzed into the uptown party, after our faces have been checked on the videophone entry system. It’s an older crowd than Wednesday night’s pheromone-fest, but no less lively. The music is Western – Daft Punk and ironic splashes of Michael Jackson and Eighties dance music – and the booze is plentiful. The choice is always between spirits. Wine provides too little bang for your buck.

The girls are “duffs”- a half-derisory term, half-admiring term for the Paris Hilton clones who congregate in the coffee houses and shops of north Tehran

The girls are dressed with more style here. The make-up is less ostentatious and the skirts designed to provoke, rather than reveal. While the women dance, the long-haired boys in the corner smoke mind-bending weed, while seeing off vodka from an Absolut bottle that never runs out. One of them is Bahram, an English literature post-graduate obsessed with the film Withnail And I. Before every shot, he clinks my glass and says, “Chin-chin, old boy.”

Around 1am, our host, the diplomat’s son, starts to get twitchy. He softens the base on the stereo, and starts drinking more heavily. “There’s a clergy who lives upstairs,” he explains/ If he came down here, he would find some warm work.

The Tehran party scene may be the by-product of a repressive state but it’s anything but a revolutionary breeding ground. When politics is discussed at these gatherings, it is only to confirm who will be voting in the elections, or whether it’s all a waste of time. No plots are hatched. But the Iranian intelligence agencies, clearly, think differently.

One student who was arrested recently on suspicion of dissident political activity (her uncle was once a member of an opposition party) says that, during her questioning, an intelligence officer listed every party she had been to in the past month. Another young photographer and socialite tells me she hears the click of a phone-tap every time she uses the landline in her apartment. Given these invasions of privacy, it is no surprise that The Lives of Others – the film about spying in the last years of Communist East Germany – is a favourite among the Tehran youth.

Jafar, a wisecracking 25-year-old pianist whose father was a member of Frozen Hot Tall, Iran’s first rock band in the Sixties, tries to explain what the parties are really about. “Tehran is out-of-control crazy,” he says. “But it’s not healthy. Everyone is doing everything to extremes. I was at a party the other day. There were 80 people there – from 15-year-old kids to old people of 75 – and everyone was so drunk it was unreal. Our use of drugs, our relationships, our parties, everything is so extreme. And, when the police come, we have to pay a lot to bribe them to go away.”

“Tehran is out-of-control crazy.But it’s not healthy. Everyone is doing everything to extremes"

Bribery is a recurring theme. Money is the only thing that can keep the authorities at bay – a fact that lowers the administrations standing in the eyes of many young people. It’s hard to brook someone’s moralising when all he wants is a back-hander. But no one complains too loudly. Sometimes, a brown envelope is the only way out of a big hole.

One story doing the rounds in north Tehran concerns a rich, gay art collector who recently threw the mother of all parties at his house in the suburbs. When the police burst through the front door, they not only found people dressed inappropriately, but a smorgasbord of drugs, including cocaine and ecstasy. The icing on the cake was the collection of irreverent artworks, including his painting of mullahs in compromising positions. The story goes that he had to pay $200,000 for the problem to go away – an unofficial record.

When Jafar asks, “Does this, what we are doing, seem normal to you?” it’s hard to know what to say. What is normal? In Tehran, normal modes of expression are impossible. Unemployment among graduates runs at 50 per cent and many with jobs are operating below their education level. The political system makes it impossible for young, secular Irainians to be heard. Meanwhile, artists and film-makers are censored or forced to take their work overseas. Musicians, like Jafar, can’t get a gig, because he needs “a thousand people to approve it, to show it’s not un-Islamic”.

One band, a Red Hot Chili Peppers take-off called Ballgard (‘helicopter” in Farsi), does its best to live the rock’n’roll life style. They drive a fleet of Shah-era Land Rovers around town and rehearse constantly in the basement of a residential block. But they are forced to travel - to Serbia, Germany and Britain – to play. Their only concert in Tehran was three years ago, an illegal “underground” gig at a kindergarten. I was amazed they weren’t angrier. “Oh, don’t think we’re not angry,” says their drummer, Ali. “Everyone in Tehran is angry. Just look at the way we drive”.

The most extraordinary victim of censorship is Reza, the only mime artist in Tehran – a lithe man with wavy hair that falls to his collar. He’s 35, has studied mime for 15 years, and attempted to teach it for ten. Through the machinations of an actor friend, he was recently given permission to instruct a small class in the basement room of one of Tehran’s universities.

“Everyone in Tehran is angry. Just look at the way we drive”

I watch the lesson. A dozen men and women in tight-fitting outfits are learning to move together. Legs entwine; faces cross inches apart. In the west, this would be as dangerous as catching a bus. Here, it’s electrifying. Reza says that if the regime saw what he was doing, they would shut him down immediately.

What kind of state wants to silence a mime artist? Reza laughs. “For them, I’m very dangerous,” he explains. “You can say a lot in mime that you can’t say out loud. And it’s to do with people’s bodies.” At the end of the class, Reza gathers his students in a circle. He wants to show them some breathing exercises. “Breathe in,” he says, “breath out.” In Tehran, that’s more difficult than it might appear.

You don’t have to be an artist to feel as if you live in a pressure cooker. In the parks, where flirtatious boys and girls come to check each other out, the police roam. The girls, in headscarves rocked back on their heads, tentatively hold hands with their boyfriends. Very occasionally, a couple sneaks a kiss. I saw the police break up one happy pair who seemed to be doing nothing more scandalous than sharing a bench. In this environment, is it any wonder things go a little crazy at parties?

Sex is a problem. Of course, it’s going on, but how? It’s rare for single, young Iranians to live apart from their parents. Family plays a central role in Persian society, and, even if you could afford the sky-high Tehran rents, few unmarried people would consider flying the nest. Young women living alone are treated with particular suspicion.

In the past, these factors meant that many people married younger, but that, too is changing. Iranians stay single for longer than ever – a product of growing disillusionment with the conservative world-view, and their entrapment between East and West. But, when even the most liberal parents balk at having girlfriends and boyfriends over to say, you can see the difficulties.

In this environment, is it any wonder things go a little crazy at parties?

The solution is to be creative. Married couples, or single friends luck enough to have their own place, are popular. Their spare rooms see some action. Travelling has also become an attractive option for unmarried men and women who want to become better acquainted. They can stay in private, rented accommodation on the way. Or, sometimes the answer is more direct. One American artist had told me he had witnessed a north Tehran party develop into an orgy, although from talking to other young Iranians, his experience seems to be the exception rather than the rule.

“Iran might be the most sexually repressed nation on earth,” says Golsa, and it’s hard to to disagree. Everywhere one goes in Tehran, people undress each other with their eyes. Markan, a 24-year-old musician and film-music composer says you can “tell immediately from how a gurk wears their hijab, what they’re going to wear to a party.” In short, it’s a city of sighs. You just need to know how to read them.

When it comes to the real thing, however, Iran remains conflicted. Take the reaction to the leak of a 20-minute sex tape, in 2006, which was alleged to be the country’s most famous actress Zahra Amir Ebrahimi (she vehemently denies being in the video). The tape, which shows a woman rather scandalously, enjoying sex in a number of positions, caused a rumpus. Religious leaders called it “a national shame.”

Ebrahimi was investigated by the chief prosecutor in Iran on charges of “corruption and prostitution”, and could have faced a public flogging or worse, but has so far not been convicted. Her career, however, is shredded. The man in the video is, reportedly, still in prison. In 2007, a new law was voted through parliament making the production and publication of sex tapes punishable by death and was passed for approval by the Guardian Council. In 2009, Iranian agencies reported that suspects are now being arrested on this charge, which suggests that the law has been ratified.

“Iran might be the most sexually repressed nation on earth”

All the while, the notorious video has been watched by millions, both on the internet and on DVD. At last count, it was the highest grossing film in Iranian history, making $4m – some achievement, given there is no copyright law in Iran.

The deep conflicts even the most liberal Iranians feel about sex and the single life have wide-ranging implications. One evening, I am accompanied to Bame Tehran, literally “the roof of Tehran” by Lilly, a traffic-stopping 26-year-old blonde, who works as a computer engineer, and lives with her parents. This is a play young Tehrani’s come to flirt. It’s a lookout spot in the mountains, from where you can see the whole city, and wonder about the private lives of 15 million people.

At the party we attended earlier in the week, Lilly was the girl every boy would have killed to dance with. She dealt with them by ignoring their attentions and throwing her hips a little more when the music took her. Now, on the walk up the mountain, she lets her scarf fall and remain at her neck for one, two, three seconds before she readjusts. But, despite her sassiness, Lilly is in funk.

Over tea, she tells me she had a boyfriend for four years, and although she could never bring him home, they “went travelling together”. In other words, she’s not prude. But she cannot see a way of moving out of her parent’s place like her older, single, female cousin has. “I have to wait for my parents to say I can,” she says. “I would never do it unless my parents were happy. And I don’t know about marriage.”

Markan is caught in a similar situation. He tells me that he travelled to Germany with his band, Dash, to play some gigs but, despite the freedoms he enjoyed there, couldn’t wait to get home. “I was so homesick for my family, I cried when I spoke to my father,” he says without shame.

The deep conflicts even the most liberal Iranians feel about sex and the single life have wide-ranging implications

Here seems to be the key to understanding the party people of Tehran. They are a generation trapped between the past and the present – a group who still believe in the importance of family, but who want the freedom to express themselves as individuals. When you understand this, you start to see the parties not as displays of Western hedonism, but as something much richer, and more Persian. They are places where everyone knows everyone. They are family.

“Thank God for these people,” says Golsa, of her friends. “If we didn’t have each other, we’d go mad.”

The plane leaves for London in eight hours, but for some reason, I’m still at Parissa’s house, drinking vodka and putting the world to rights with her genial boyfriend. It’s midnight and the “quiet dinner” has turned into something altogether fruiter. Some of the girls have started dancing, and someone’s ordered pizza. It’s Sunday, the equivalent of a Tuesday night in London, but even those with jobs to go to in the morning will be here for hours.

Why does everything have to turn into an all-nighter? “When you’re forbidden to do anything normal,” says the hostess, “you express yourself in exaggerated ways.” Another drink is poured. Bahram, the Withnail And I man, has turned up. “Chin-chin, old boy,” he says. There’s some romance in the corner. Another shot. Take off in four hours. Shouldn’t I get some sleep? A girl approaches. I tell her my situation. She tells me to “sleep later, have fun now”.

It is the mantra for a generation.

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