As conversations you don’t want to have as a teenage boy with your mother go, one that begins “Sweetheart – I’ve noticed you’re pretending to masturbate” is right up there. But such is your lot when you are 16-year-old Otis (Asa Butterfield) and your mother is Jean (Gillian Anderson), a sex therapist whose work has brought enough unwanted knowledge into the home to have turned you off sex – even sex with yourself – for life. Otis has been planting evidence of standard teenage behaviour in his room to avoid maternal attention in this matter. Poor Otis.

But this beleaguered boy will shortly be taken up by badass cool girl Maeve Wiley (Emma Mackey), when she spots a lucrative opportunity to charge for the sex counselling skills he has unavoidably absorbed in a marketplace of anxious and furiously active teenagers.

Sex Education (Netflix) is a rare thing: it’s a series that foregrounds sex (literally – I thought one of the boobs in the opening scene involving schoolboy Adam and his girlfriend was going to take my eye out) only to let it illuminate everything beyond. Every character could easily be a stock, risible one – the teens could just be horny, Jean could just be embarrassing, Otis just a nerd, Maeve the manic-pixie-dream-girl love object we’ve seen a million times before. But none of them are, in this immaculately, densely written, glorious creation – her first for TV – of playwright Laurie Nunn.

And it’s funny. Endlessly and seemingly effortlessly funny, in a naturalistic way that doesn’t have you listening for the hooves of the next gag thundering down a well-worn track but, like Catastrophe, catches you almost unawares and makes you bark with laughter. And then, like Catastrophe, it can pivot smoothly and suddenly into moments that give you a lump in the throat and have you staring at the ceiling trying not to let your tears fall because crying would surely be ridiculous.

The sudden, flattening fear that comes over the normally ebullient Eric (Ncuti Gatwa), Otis’s gay best friend, when he sees bully Adam coming towards him, and the moment it takes him afterwards to recover, are just heartbreaking. All the performances in Sex Education are absolute wonders, by the way, but Gatwa is something particularly special. He is real, unaffected, joyful, with perfect timing and understated emotional heft. I hope this is the breakout appearance for him it promises to be: I want more of him on my screen as soon as possible.

Solving Adam’s problem (his clinic notes would read: “big penis, can’t come”) is what kickstarts Otis’s new career. Adam, despite being the headmaster’s son, is none too bright even before the blood rushes to his penis. Thinking Viagra will solve his orgasm difficulties, he takes three. Otis and Maeve hear his groans coming from a cubicle in the abandoned toilet block. “I feel lightheaded,” he says, clutching the doorframe. “And I can taste scampi.” Now there’s something that will take your eye out.

To distract him, Otis asks what led to this drastic course of action, and out his tale of woe comes. Otis offers his advice (“The myth surrounding large cocks is affecting you, and the visibility of being the headmaster’s son. Those things can’t change but your outlook can. I think you need to own your narrative”) in exchange for Adam laying off Eric.

When Maeve hears via the female information exchange that Otis succeeded where Adam’s girlfriend’s hard work and enthusiasm had failed, the hunt for new clients is on. Otis even finds himself emboldened. “Mum, I can’t masturbate. I don’t want to talk about it. I’m dealing with it on my own,” he says. Jean pauses, nods acquiescence and says: “Thanks for telling me.”

I know it’s early but if there’s a better, sweeter, punchier comedy this year then, for sure, 2019 is on Viagra too.