“I had got to a point before this happened where I was thinking about retraining. I’d just turned 30 and I thought, I’ve been doing this for so long and I can’t see it happening.” This frank admission by Laurie Nunn might bring some comfort to the thousands of other aspiring writers, hoping to emulate her apparently instant success and become Netflix’s next creative wunderkind.

On the face of it, hers is a fairytale story of an overnight phenomenon – with just four previous entries on IMDB and all of them including the word “short” in brackets, Nunn is the creator and writer of Sex Education, the zeitgeist-surfing teen sex comedy watched by 40 million viewers within the first four weeks of its release in January last year. The show was almost instantly recommissioned for a second series, which streams this month.

But she’s quick to add that the ­sailing, even on this project, wasn’t entirely smooth: “We couldn’t really find a home for it, people didn’t know what to do with it. I thought it had died a death, and then it ended up in the hands of Netflix and it came back to life, which was wonderful for me.

“Before that, I’d had lots of stuff in development, and things would get very close to a green light, but then somebody would leave their job, or the money would fall through…,” she shrugs. “That’s just the way it is in the industry, but I do believe that if you keep at it, you’ll have the right story for the right moment.”

With Sex Education, she definitely offers a show for the moment. It pays nostalgic homage to the ever-popular screen staple of teens going into battle with their hormones, while bringing it bang up to date with its serious discussions of sexual politics and contemporary attitudes towards relationships.

‘I had the skills in terms of writing… but everything else I just had to learn on the go’

“I realised very quickly that it was an amazing opportunity to have a frank but funny conversation with a younger audience,” she says. “The conversations happening at the moment in that area are interesting, and moving so quickly, it felt a timely thing to do.”

At the centre of the show are Otis, his gay best friend, Eric, and elusive love interest Maeve. Asa Butterfield’s Otis is as squirm-ridden as you’d expect for a 16-year-old schoolboy with a divorced sex therapist for a mother – Gillian Anderson clearly relishing the shock value of her role – but soon turns the knowledge he has inherited from her to good use.

He provides a sex counselling service to everyone else in the school, inevitably with one exception – his earnest self. Nunn is happy to admit to some personal inspiration. “Otis is probably the closest to me. I grew up with a single mum. She’s not a sex therapist, but the real intensity of that single-parent relationship is very familiar to me. In many ways, the mum’s the bad boy.”

Maeve, a sweet but bruised loner played by Emma Mackey, is also inspired by Nunn’s own childhood. “My closest friend in Australia, my best friend in high school, had the bad end of the stick with her family. She was that kid in school who can’t get a break because of the situation they’re in, so I wanted a character who reflected that survivor spirit.”

In thinking up the sexual antics and awakenings that arise, often literally, through the series, Nunn happily harvests the collective awkward-­memory consciousness of her writers room.

“There are about seven of us in the room, and a lot of the material comes from that,” she reports. “We sit in that room for five weeks – my friend describes it as the world’s longest dinner party.

“We try to create a very safe space for people to share, as the content is very sensitive. But you realise really quickly that those teenage stories, they’re all similar. You’re always coming back to, ‘What did I want to know when I was 16?’”

Despite all the horror-fuelled jokes, the message of Sex Education is a sincere one. “At the heart of the show, it’s just very much about trying to be more open, to communicate more,” says Nunn. “I’m trying to show (especially male) characters who can talk to each other in an open, honest way.”

And, of course, in this era, on-screen diversity is key, including black, gay Eric (played by Ncuti Gatwa) who comes out in true diva fashion at the school dance with the belated support of his father.

Nunn reveals that two writers contributed to the storyline because of “Eric’s intersectionality – I’m a white female, I wouldn’t presume to know what he was going through”.

She goes on: “Eric was the only character written so specifically. With everyone else, we felt that anyone could play the characters, but the show is about universal experiences, and I felt everyone should be able to see themselves on screen. I wanted to take the genre and update certain parts of it.”

This contemporary attitude, as well as the predominantly British cast, sits in contrast with the timeless, US-centric look of the show. While the bright colours, varsity jackets, swimming teams and school dance could all have come straight from Fast Times at Ridgemont High or the Rydell High School of Grease legend, Nunn was always aiming for “a larger-than-life world” to accommodate her story.

“I felt the script always had a heightened feeling to it, so, when Ben [director Ben Taylor, fresh from Sharon Horgan and Rob Delaney’s Catastrophe] came on board with that vision, it all made sense to me. We both had a similar love of the teen genre, so it really came out of that conversation.”

Some of the rare criticisms of the show have focused on this aspect. “The conversations about the Americanness of it, that negativity, surprised me. But, as a team, we felt strongly about that decision and I still feel good about it,” Nunn says, before rolling off her own teenage favourites, which clearly inspire her work – Freaks and Geeks, Dawson’s Creek, all the John Hughes films plus the one movie she holds most fondly, 10 Things I Hate About You.

“It’s so funny and very feminist, not ham-fisted, and also, Heath Ledger is just dreamy,” she finishes, suddenly sounding just like the teenagers she so successfully channels.

It’s tempting to assume that it must have all been very straightforward for Nunn, daughter of acclaimed theatre director Sir Trevor and his second wife, Australian actress Sharon Lee-Hill, to climb up the family ladder to creative success.

But, while she describes a childhood surrounded by storytelling and theatres – “in a pretty non-glamorous way” – it also took her to the other side of the world, where she began carving out her own path.

Aged 14 when her parents divorced, Nunn moved to Australia and studied for her first degree in film in Melbourne, before returning to London in her early twenties and embarking on more studies.

“When I finished my first degree, I realised I was quite young and it was hard to get stuff made,” she remembers of her first wake-up call. “I wasn’t quite prepared for it, and then that was around the time I was getting into TV box sets and I realised this form of storytelling was really speaking to me.

“I applied to the National Film and Television School for a screenwriting course and that was a great experience, very industry-focused.”

One of those who spotted Nunn’s college work was producer Sian Robins-­Grace, then at production company Eleven and working on the seed pitch for what would become Sex Education.

‘I had an extended panic attack… I had to fake it to make it’

From that one fortuitous meeting, Nunn now finds herself in the extraordinary position of not just sitting in a writers room for the first time, but actually leading it, and on a massive global TV hit.

“I’d never been able to get into anyone else’s writers room, so when I was asked to create my own, I genuinely had no idea what I was doing. I basically had an extended panic attack that lasted for about five weeks. I had to fake it to make it,” is how she remembers those first heady days. “There have been pros and cons. At first, I was just making it up, but I’ve been able to create my own way of doing it. I don’t know how other people do it, but it works for me. I had the skills in terms of writing the scripts, but everything else, I just had to learn on the go.”

Nunn’s future looks bright, with offers dropping in on the back of her unheralded success, and she has one eye freshly on the prospect of returning to her teenage passion of directing. For the moment, though, she remains consumed with Sex Education.

With the second series about to air, she’s waiting to hear whether there’ll be a third, but has already started writing. “Nothing much has changed. I’m still living in the brain of a 16-year-old.”

At home in north London, she describes creating the first draft of her scripts as the most painful part – “Once I’ve got something to craft and make better, I start enjoying it” – and is easily distracted by true crime documentaries and box sets. “Six Feet Under is my favourite show of all time, I always go back to it.”

From her current position, she can afford to be philosophical about her years of effort before Sex Education arrived. “When I first wrote it, it wasn’t the right moment but, five years down the path, it was.

“Most things in this industry take quite a lot time. You have to have persistence. The hardest things are keeping up your self-belief and putting your ideas out there, but I’m glad I stuck it out.”