Claire Skinner

Outnumbered's spot-on portrayal of middle-class family mayhem is the very thing that can tip it towards the irritating. Over its three series, the joke has remained resolutely the same: given the right socio-economic background, precocious children will say the funniest things. And while there's always enjoyment to be had from the eccentricities of the Brockmans, there's now no escaping the faint whiff of the formulaic. In the final episode of the series, Pete (Hugh Dennis) deals with the fallout from his drunken infidelity and Jake (Tyger Drew-Honey) embarrasses himself with the baby-sitter. And there's a rare moment of tenderness when Sue's (Claire Skinner) latest obsession leads to Karen (Ramona Marquez) having an accident. "I've nearly killed the kids loads more times than you have," comforts Pete.

The fifth episode of the third series of the family comedy maintains the good form of last week's, fuelled by an early confrontation between Pete (Hugh Dennis) and Sue (Claire Skinner) and the typhoon-like arrival of Sue's sister Auntie Angela (Samantha Bond) and her ghastly American psychologist of a husband, Brick (Douglas Hodge). That's before an awkward restaurant meal dredges up Angela and Sue's acrimonious history. As usual, daughter Karen (Ramona Marquez) has her own opinion on the matter, deftly using her ingénue quips to throw a cold light on adult hypocrisy.

This is one of the funniest episodes to date. Last week, you may remember, Dad (Hugh Dennis) had woken up with a crippling hangover after a night out that involved green cocktails. It gets worse. It turns out that he danced with a woman called Mimi who kissed him - and he kissed her back - and now his wife (Claire Skinner) has found out. One way and another it could hardly be a worse time for the unspeakable sister (Samantha Bond) to arrive for a visit with her new boyfriend, an American therapist with a ponytail called Brick (Douglas Hodge). They all go out for a meal and the evening degenerates into a classic middle-class bloodbath, during which little Karen (Ramona Marquez) dissects the ponytail's psychobabble with lethal precision.

Pete has disgraced himself. In a moment of drunken folly he has brought shame on himself, on Sue and possibly on the whole family. As you'd expect, the scene tonight where Sue confronts him about it is one of the best in the series so far. Claire Skinner does simmering rage better than most - just look at the way her eyes shoot daggers at Pete. And look, too, at the way Hugh Dennis saves Pete's most panicky look for when he realises he'll have to discuss the whole thing with 13-year-old Jake. This little contretemps serves as backdrop for the return of one of Outnumbered's old hands - Samantha Bond as Sue's infuriating sister Angela. Since we last saw her, Angela has married a pony-tailed American therapist (Douglas Hodge) and become mother to his children: "We have five kids," she announces to Sue, with classic sisterly oneupwomanship. The comedy in the awkward restaurant meal that follows is a teeny bit forced, but there are plenty of choice moments in the episode. As Angela says, annoyingly, "There's such wonderful energy in a big family."

The family-centred improv' comedy has been a bit patchy of late but this episode is a corker. Tonight it's not just the kids who have been misbehaving, as Sue (Claire Skinner) discovers when she checks Pete's (Hugh Dennis) mobile for messages. But there's no time for a heart-to-heart when the kids are about.

If it's not Jake (Tyger Drew-Honey) turning the garden into a watery war zone, it's Karen (Ramona Marquez) asking if it's ever OK to hit a classmate.

Meanwhile, Pete's worried about the impending clash as Sue's sister Angela (Samantha Bond) turns up with her new husband (Douglas Hodge). While the adults struggle to remain civil, the children call a spade a spade - or, in Jake's case, reel off 18 names for a part of the male anatomy. Nudity and toilet habits also feature - but that's kids for you.

Indeed, some families might see this comedy more as a documentary. A funny one, mind.

The fourth episode of what has been an inconsistent third series of the sitcom following the travails of the Brockman family. Sue (Claire Skinner) is trying to prepare the house to show around potential buyers, at the same time as Pete (Hugh Dennis) gets ready for his colonoscopy while hung-over from a drunken night out. The children are up to their usual mischief, with Karen (Ramona Marquez) refusing to go to school and Ben (Daniel Roche) in trouble for playground antics. Though the show feels as if it's winding down as the children grow more knowing, on the form of this episode it remains more inventive than most of the competition.

Once again Outnumbered provides half an hour of pure happiness. The episode begins with the two brothers at loggerheads. The younger one, Ben (Daniel Roche), has changed his brother's status on Facebook to "Jake is a transvestite", so Jake (Tyger Drew-Henry) responded by changing Ben's Facebook status to "Ben died on Tuesday". Meanwhile Dad (Hugh Dennis) struggles to explain to the children what a colonoscopy is ("Will we be able to watch it live on television?"), while Mum (Claire Skinner) makes a doomed attempt to try and explain to her 13-year-old son what is meant by the objectification of women. It's consistently funny, but best of all is the adult tennis match featuring Ben as a ball-boy and seven-year-old Karen (Ramona Marquez) as the referee.

One of the boys has been downloading "inappropriate" images of their teacher, which leads to an awkward family discussion about the meaning of inappropriate. But Dad (Hugh Dennis) tries not to worry. "They're just teenage boys," he tells his wife (Claire Skinner). "They're like baboons on heat. In school uniforms." Elsewhere in the house, five-year-old Karen (Ramona Marquez) is busy writing letters to President Obama. "I am beginning to lose my patience . . ." she begins. She is also developing a tough-love approach to prison reform. Prisoners, she says, should be put in holes in the ground. Occasionally soup should be poured in, forcing them to scoop it up in their hands. The trouble with children is that they don't appreciate the value of political correctness.

Time for series three, and yet again we ask the same question - how is it possible for child actors to be this funny? Episode one opens with Ben and Karen on a London sightseeing trip pondering how lions assisted during the Battle of Trafalgar and 'that king who thought he was made of glass', while parents Hugh Dennis and Claire Skinner do an excellent line in bewildered.

The funniest kids on TV are back for a third series. But has Outnumbered become a victim of its own success? Back in 2007, when this was buried apologetically in the schedule's nether regions, there was a real novelty about small children being allowed to dictate proceedings. Now, after bagging three gongs at the British Comedy Awards last year, tonight's episode feels like an extended stand-up gig for Karen and Ben (Ramona Marquez and Daniel Roche).

You sit, arms folded, thinking, "Come on, then. Say something outrageous." Naturally, you don't have long to wait but the bits with the adults in between can feel like a distraction from the main event. That's not to take anything away from the show - just a sign of how hard it is to stay ahead of the game in comedy.

The Brockmans are on a sight-seeing trip around London tonight - an opportunity for Mum and Dad and Gran to be mortally embarrassed in front of a variety of internationally-recognisable landmarks. And from the one-liners the kids come out with, it really can't be much longer before they're invited on to the Have I Got News For You panel.

There are jokes about Gordon Brown tonight and the death of Diana that might have provoked howls of outrage if they were uttered by an adult. They still might but the power of these kids is that they can get away with anything - as their beleaguered parents (Hugh Dennis and Claire Skinner) know only too well.