Chris Reddy's delightful comedy revolves around Laura (Scarlett Alice Johnson) trying to cope with becoming pregnant after a one night stand with 16-year-old Jamie (Sean Michael Verey). As Laura heads off to Edinburgh University, she believes that she can put her "situation" to one side - but is followed by Jamie.

Another charming episode proves last week's opening part of this new comedy wasn't a one-off. Newly pregnant Laura (Scarlett Alice Johnson) is still grappling with the full consequences of her one-night stand with 16-year-old Jamie (Sean Michael Verey) when her parents (Angus Deayton and Anna Chancellor) find out - in less than ideal circumstances.

The attractiveness of the British teenager may be as hard to detect as the Higgs boson particle, but it doesn't stop TV producers from putting more and more of them before the cameras for our inspection. Following the success of Skins and The Inbetweeners comes Pramface, a comedy of virginity, sex and pregnancy (yes, in that order) among the GCSE-sitting classes, and the discomfiture of their parents.

Sweet-faced but lecherous Jamie (Sean Michael Verey) and his conceited babe-magnet friend Mike (Dylan Edwards) are 16, have just finished their exams and are anxious to crash a party thrown by cooler and more grown-up schoolkids. "There may be scenes of a sexual nature," confides Mike, who wears green shirts with Harry Hill collars, sprays Lynx in his underpants and has made a shag-along soundtrack on his iPhone that ends with the theme to Top Gear. Elsewhere, pretty, 18-year-old A-leveller Laura (Scarlett Alice Johnson) has been grounded for smoking dope. She has a turn of phrase that shocks her anxious parents, Anna Chancellor and Angus Deayton: "It's not as if you found me snorting coke or straddling my pimp"; "To you the world's just one big fucking naughty step isn't it?" Naturally she escapes the prison of home by falling out of the window and at the posh party she drunkenly kisses Jamie. Minutes later, they are dancing the blanket hornpipe on a leopardskin throw in someone's bedroom, while Jamie's girlfriend Beth attempts to crawl out the door.

Weeks later, along with her A-levels, Laura gets another result: she's pregnant. She has no recollection of her inamorata, only a phone number. When they arrange to meet in a café, she makes for the promising-looking chap sitting by himself, but gets it wrong: the father of her child is the geeky kid at the other table. Oh, no! He's 16, she's 18 - an unbridgeable gap - she has a croissant in the microwave and their young lives are blighted for ever. Or are they?

Chris Reddy dreamt up Pramface and wrote the script, directed by Daniel Zeff. It has nice touches: when Laura rings the number scrawled on a note, to say, "We slept together and now I'm pregnant", she dials the wrong number and her voice is beamed to the phone-speaker of a car driven by a startled bourgeois with his family. But it's all so derivative. Do we need any more jerking-off jokes, orgasm faces, drunk-girl pratfalls? There's a deal too much Americana here too: the plot's straight from Knocked Up; the party scenes of interchangeable babes owe a lot to Beverly Hills 90210; Laura's taut family supper echoes American Beauty. Lacking the rude conviction of The Inbetweeners, it comes over as The Hand-Me-Downers.

Pramface: Playing the pregnant teenager

Scarlett Alice Johnson who plays Laura Derbyshire in BBC Three sitcom Pramface, talks about playing a pregnant teenager.

Bucking the usual BBC3 trend for hand-to-mouth budgets and scruffy single sets, this has a massive cast, gorgeous houses you'll want to nick decorating tips off and its low-level smut is cushioned by some genuinely LOL-worthy moments.

Setting its stall midway between the cringe comedy of The Inbetweeners and too-cool-for-school Skins, it stars two ex-EastEnders: Scarlett Alice Johnson, who you definitely won't recognise as Vicki Fowler, and Emer Kenny (minus Zsa Zsa's blue hair extensions and stroppiness) who you probably will, as well as newcomer Yasmin Paige.

On the boys' team are Dylan Edwards and Sean Michael Verey.

I could tell you which pair of teens end up expecting a baby by the end of this episode, but that would spoil the surprise.

A second series has already been commissioned. Quite right, too.

In Pramface (BBC3) a potentially clunky premise - two teenagers' drunken sex at a party leads to a pregnancy neither is ready for - is saved by cunning casting and a funny script. Sean Verey as 16-year-old father-to-be Jamie has scarcely lost his puppy fat, while as 18-year-old mother-to-be Laura, Scarlett Alice Johnson looks and plays like a young Harriet Walter - as hard as nails in dealing with her convincingly useless parents (Angus Deayton and Anna Chancellor), yet as brittle as pressed flowers with everyone else. I loved Jamie's loser friend's hopeless sex playlist - 50 Cent followed by the Top Gear theme tune. Although Chris Reddy's plot is full of holes (would Laura, after discovering she's pregnant, really make her first phone call to the shag buddy whose face she can't recall?) there is enough in this too-much-too-young comedy's opening episode to justify a second date.

BBC Three's comedies are often more miss than hit but you suspect Chris Reddy's new six-parter is a winner. A likeable cast and a witty, knowing script play out a storyline which opens with 16-year-old Jamie (Sean Michael Verey) and maladroit mate Mike (Dylan Edwards) heading for a post-exam party. Nervous Jamie is seduced by 18-year-old Laura (Scarlett Alice Johnson) with unexpected consequences.

Scarlett Alice Johnson interview

Scarlett Alice Johnson first found fame as Dirty Den's daughter Vicki Fowler in EastEnders. What's On TV magazine caught up with her to find out why she thinks her new BBC3 comedy Pramface could become a cult hit...