The problem with attending a course about writing sex scenes is that everything becomes a double entendre. In this, the course, run by the Raindance Film Festival, doesn’t help itself. An A4 piece of paper, masking-taped to the door outside: ‘FOR RAINDANCE HOW TO WRITE SEX SCENES,’ it says, ‘HEAD DOWNSTAIRS’. And so, down a narrow, deep-red passageway, I head.

There’s no shortage of classes teaching wannabe writers how to write books and scripts: ones that teach you about plot, character development and how you’re destined for a life of disappointment and ordering wine from the top of the menu. But a course specifically about sex? A course about the in-and-outs of the in-and-outs? I had to attend. The room is bedroom-small; there are around 30 of us. In front of me, a man scrawls, ‘How to write sex scenes’ on a Kindle-like device the size of an A4 pad in handwriting so large he needs to turn the digital page to record any further information.

The first thing we are told, by the teacher Natali Simmonds, is that it’s perfectly okay – encouraged even – to be aroused. Not now, you understand, but when writing. If it’s turning us on, Simmonds says, it’ll likely turn the reader on too. Don’t think: feel.

‘When you’re writing an emotional scene, do you cry?’ she says, by way of explanation.

Simmonds is in her mid-40s, half Spanish and a prolific author of both twisty thrillers and romantasy books where sexy werewolves get it on with witches. It was the latter, she tells me later, that lead her to first teach sex scenes over YouTube in lockdown; it has since become a side-hustle.

Her aim is to both demystify and destigmatise. She throws an opening question: who’s been scared of writing about sex until now? A slim, broad-­shouldered young man in the front ­row answers.

‘Sometimes I’m worried people will think what I’m writing is what I like,’ he says in an Essex twang. ‘And get accused of it: oh, you like that, do ya? Like, no, I don’t like that particular thing.’

We all silently wonder what that particular is and why he likes it so much. He’s writing, he later tells the class, a ‘very cartoonish’ comedy called The Virgin Essex Girl. Like The 40-Year-Old Virgin, he explains, but Essex.

A larger, older man to his right, whom I later learn won a competition to be here, takes a different tack.

‘I think it’s: how far can I go?’ he suggests. ‘You have these fantasies, it’s how far you can bring that out?’

‘Or,’ says Simmonds diplomatically, ‘is your screenplay or book the place to put that?’

When Simmonds first started teaching sex-lit, she imagined the classes would solely be populated by young women working on rom-coms. The reality, as displayed by those in attendance here, is more diverse: more women than men, sure, but only a 70–30 split. Ages range from mid-20s to late-50s.

Embarrassment, says Simmonds to the class, leads the novice sex writer to rush things. There’s not enough build-up, or simply not enough sex, their itchy typing fingers hovering over ‘fade-to-black’. They just want to get on with the plot: premature exposition. Instead, she says, we should regard writing about sex much like sex itself: don’t rush it, people don’t want to feel cheated. To hear Simmonds tell it, there are broadly two types of sex scene: ‘Early Sex,’ and ‘Late Sex.’ Most plots, she says, follow it. Late Sex is where you spend most of your book or film building up to it, ‘and by 80 percent [through] just give the audience what they’ve been waiting for.’ Early Sex is where sex happens relatively quickly, and therefore causes problems down the line.

Think Before Sunrise is a romance about kindred souls offering differing views on mortality and meaning? I mean, sure. But that knee-trembler in the park towards the end makes it a Late Sex plot. Sally Rooney’s Normal People, on the other hand, might be a heady mix of modern Marxism and yearning. But it’s also an Early Sex story. Pretty Woman is classic Early Sex.

Good Sex can practically be plotted on a graph. Simmonds doesn’t like to be too formulaic about these things, but allows a formula based on one of her paranormal romances. Six per cent in: give some small hint. 30 per cent: let the reader broadly know who – or in this case, what – your protagonist will end up in bed with. 60 per cent: a snog. 80 per cent: getting it on. Do not rush things. ‘If you give it to them in the middle of the book, they haven’t got much to look­forward to.’

The irony about attending a sex writing course is that young people are having sex less than ever before. In the UK, the latest figures from the National Surveys of Sexual Attitudes and Lifestyles study shows a sharp decline among those aged 16–44. In the US, the Institute of Family Studies report that sexlessness in young women has risen by 50 per cent over the past decade. For young men, it’s doubled. Yet at the same time, in fiction at least, we’ve never wanted it more. UK fiction revenue recently passed £1 billion thanks in large part to filth. Hashtags like #smuttock and #monsterromance trend. A book called Under Loch and Key sees a woman banging the Loch Ness Monster. It clocks in at nearly 500 pages. Gen Z haven’t so much ditched sex as outsourced it. The questions people ask on the course reflect this, in that they’re remarkably diverse, frank and often unexpected. A young Irish woman wants more disability in sex scenes. Not just physical (‘You have to start to get creative’) but cognitive. Those like her, she says, with autism, are often hyper-sexual, a fact I did not know, and so store away for use at parties.

Eventually, we land on that thorniest of artistic questions, made all the more thorny when it comes to sex: should you just write what you know? If not, might one be accused of sexual appropriation? The consensus seems to be… maybe? At the very least, Simmonds suggests, one should do due diligence. Speak to the people you’re writing about. The author of The Virgin Essex Girl spots an opportunity. ‘So, I’m not a girl and not a virgin. Should I talk to–’

‘They don’t have to be virgins,’ jumps in Simmonds, ‘but you should run it past some women.’

But what words should you use? Can a member throb? Should a vagina be moist? ‘I keep reading “moist cunt” all the time,’ says the woman into daddy-dom lit. No, Simmonds explains, it’s not an action scene. It’s about building tension, crafting character. You’re not writing a sex manual.

‘If a hand goes under a skirt,’ she tells the class, ‘we know what’s happening.’ A couple of guys write this down.

A young, lightly bearded man in a hoodie on the row behind me has come to a bottleneck in his script, he tells the class. He’s writing about a middle-aged man who sees a lost love win an Oscar and attempts to win her back. For the eventual sex scene, he’s been trying to depict it as if they’re 17 again, to show their former connection, with dispiriting results.

For Simmonds, this is not a three-­pipe problem.

‘You don’t make it about sex,’ she says, ‘you make it about connection. So, he might have given her a little crystal, and you don’t think much of it. And then, when they undress, she’s had it put into a necklace, and he realises she never stopped thinking about him.’

When I later speak to Simmonds, she says she’s always amazed how she can tell a sex scene written by a man a mile off. It’s almost always, she says, about the physicality of the act, not the emotion of it. ‘They’ll be just describing what the man looks like, or describing the ­woman’s breasts.’

Simmonds points out that the sexiest scenes often involve no sex at all. For her romantasy books, she writes under the pen name Caedis Knight with co-­author Jacqueline Silvester. And sure, she allows, they recently wrote a scene involving ­cunnilingus of the gills. But the favourite sex scene she’s written? That would be one involving two witches. One witch simply paints the other’s portrait, the twist being her ­magical brush lets the other feel every stroke. They gaze at each other. But they don’t actually touch. ‘And that for me,’ says Simmonds, ‘was sexier than anything else.’