Have you heard the one about the comedy school?

Who said being a comedian is just for the grownups? Tim Dowling takes his son to the School of Comedy to help him hone his budding comic skills.

This E4 sketch show by youthful comic actors had its flaws but was undeniably endearing. Now C4 viewers can get in on the silliness of series two. It's mainly worth catching for a dose of standout star Will Poulter, who, with films such as Son Of Rambow and, most recently, The Chronicles Of Narnia: The Voyage Of The Dawn Treader to his credit, looks to be a young lad who is going places.

School of Comedy expands after E4 success

School Of Comedy, the Chiswick-based youth theatre club that spawned the E4 series of the same name, is to build on its success with the opening of two new London offerings in 2011.

The series where schoolkids act out comedy sketches as adults may not be to everyone's tastes, but I enjoyed the first series and the second seems to build on what they achieved first time round. I saw the first couple of episodes at a screening last week, and Jack Harries as the world's worst best man and Beth Ryalnce's blind woman with a long-suffering husband (Will Poulter) were definite highlights. One thing that did irritate last series was the intrusively hysterical laughter track - there was so much genuine laughter in the screening room that I honestly can't say if that has been toned down.

Review: School of Comedy series two

The kids are as funny as last time, but the stand-out performance comes from Beth Rylance as Angharad, an irredeemably rude, blind, welsh woman who takes out her frustration on her doting husband Gerald.

The gimmick of teenagers playing adult roles in this sketch show is kind of strange. It's not like there's a shortage of grown-up comedians or actors out there; we're over-run with the darn things.

But surprisingly, it works much, much better than you'd expect.

Clichéd set-ups - like arguing middle-aged couples, and white van men (or ven men as we must now call them thanks to Peep Show) shouting incomprehensibly at passing women - are completely rejuvenated when played by these youngsters who are way funnier than they have any right to be.

The jazz-age lesbians were hilarious but a lot of the attention will fall on the brilliant 16-year-old Will Poulter, who starred in Son Of Rambow.

If I were a 40-year-old comedy actor, I'd be very, very worried indeed.

As part of the relentless drive towards eliminating the older generation from our screens, Channel 4 has given the much-coveted 10pm slot on E4 to a group of whey-faced schoolchildren, so that they can get their lisping adolescent chops around some precocious sketch comedy. But don't worry, readers: although their faces are young, their material is incredibly old. As an audience presumably composed entirely of members of their immediate families hoots hysterically, they trot through various fresh and original sketch-show tropes, including black-cab drivers, bumpkins, barristers and Brief Encounter. And if that fails (which, you can be sure, it frequently does) they swear. What's funnier than a child swearing? Nothing, your honour.

This programme does, however, boast one magnificent joke: the warning that it might contain "adult humour". How we laughed.

More youthful dynamism over on E4, where a group of precocious teens display their blossoming talent in a new sketch-show, School of Comedy. Presumably, this is what David Walliams was like as a youngster. Annoying. And not that funny (no change there, then). To give the kids their due, not all of the attempted sketches were terrible. Indeed, the opening one, set in a primary school parent-teacher meeting, had me laughing out loud, as did the barrister who won over his jury by hypnosis. The problems come when they returned to the same set up for a second (and, sometimes, a third sketch). Hypnosis is funny. Not so much when he got out the Ouija board and even less so when Barry Manilow came out. You forgive them because they're only kids after all - and even at their worst they're still funny in an aren't-they-cute-in-the-school-play kind of way. But then, hang on, you think: what exactly are they doing on my telly? Especially at 10 o'clock at night. Someone, somewhere has some very powerful parents.

The young performers in School of Comedy may have also misfooted you. The teenagers performed sketches more familiarly performed by adults. The audacious success of this first episode was making the performers' youth - whether the sketches were good, bad or middling - immaterial. They were comedians first. The humour was juvenile (mirroring a lot of adult humour rather than reflecting their age) and sometimes very funny.

One of the best characters was an offensive teacher who delighted in being vile about the children. "He sounds like a girl when he talks," he joshed one boy's parents. "What is your policy on bullying?" an Ofsted inspector asked him. "Yes, definitely," he replied stoutly.

An over-excited taxi driver bored his passenger to tears with a stream of verbal diarrhoea about "Rageh Omaar slow dancing with Gloria Hunniford" in a dizzying, and grating, avalanche of celebrity name-dropping. There was a delicious sketch in which a doctor delivered the awful news to a patient that she had six weeks to live and showed her the X-ray with a telltale shadow on her lungs. But the shadow turned out to have been cast by a pot plant on a nearby windowsill. "You're going to be fine. Sometimes these things clear themselves up," the mortified doctor said. A man showing a couple around his house, which was for sale, warned them that one room was old-fashioned, then opened the door to reveal a group of characters in a black and white film.

There were some duff sketches - the fact that two security guards are from South Africa doesn't seem intrinsically funny - but a final sketch proved the School of Comedy's high pass rate. A defence counsel launched into a voiceover rendition of Copacabana, with a convincingly attired Rico and Lola, to free his client. Silly and brilliant.

I generally only find children funny if they're being catapulted off a see-saw into a dung heap on You've Been Framed, so I approached School Of Comedy with caution. The idea of a bunch of precocious baby actors pretending to be adults in a bunch of sketches smacked of overindulgence, an idea best restricted to an end-of-term high-school skit, not granted a whole TV series.

Yet, though it had its iffy moments, School Of Comedy is laugh-out-loud funny. That's principally down to the rubber-faced Will Poulter, of Son Of Rambow, who is surely a star in the making. Segueing effortlessly from dunderhead schoolteacher to South African security guard by way of a defence lawyer with a neat line in hypnotising juries, Poulter gave a masterclass in comic timing and nifty accents. The rest of the cast are fine but this is Poulter's gig: the boy deserves his own show.