Ramona Marquez

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.

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.

Dad (Hugh Dennis) has woken up with a crippling hangover having being ambushed by bright green cocktails. His youngest son, Ben (Daniel Roche), is bitterly disappointed that he missed the sight of his father being sick. "Your face is all grey," he says, "like someone shaded you in with a pencil. You smell like the relief teacher who didn't last very long. The one with the shaky hand who kept bursting into tears for no reason." Because the day of Dad's hangover also happens to be Friday 13th, Karen (Ramona Marquez) is refusing to leave the house in case something bad happens and she is eaten by bears on the way to school. And to cap it all, this is the day that house hunters are coming round to view the house. Once again, Outnumbered provides half an hour of pure happiness.

It's Friday the 13th and superstitious Karen refuses to go to school in case something bad happens. She might, she insists, get mauled by a bear. Ben, meanwhile, asks his hungover father, "Dad, what's the point of living?" So just another day in their household. It's probably heresy to say so, but the series is starting to feel just that little bit predictable. But then complaining is churlish when it's given us Ramona Marquez (Karen), the best female comedian currently on the telly.

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.

Outnumbered success relies on the partly improvised dialogue derived from the interaction of the three children and their screen parents in various situations: in last week's episode, a trip round London with dad Pete's mother in tow. The youngest, Karen (Ramona Marquez), nine, is the star, her dialogue pursuing paths of childish logic to which Pete (Hugh Dennis) reacts with probably real bafflement. In previous series the adults had more of the screen; here they are pulled into the background more as feeds for the self-confident kids, no doubt ruminating on the phrase attributed to WC Fields, "Never act with children or animals".

At last - the family sitcom that reinvented family sitcoms returns for a third series. Back in 2007 Outnumbered was a blast of suburban fresh air; with its knowing kids running rings around bewildered adults, it felt dramatically and hilariously more real than anything that had gone before. It feels fractionally less fresh now but just as funny, as we rejoin the Brockmans on a sightseeing day out in London. Very soon, scarily precocious Karen (Ramona Marquez) is grumbling that she wants to go somewhere "more World- War-Two-ish" while uncontrollable Ben (Daniel Roche) is climbing on one of the Trafalgar Square lions and stabbing it with a ruler. "Die!" he shouts. "Die, Aslan, die!" Throughout, dad Pete (Hugh Dennis) wears his fixed expression of pain and confusion, like a baited bear. As a portrait of parenthood, it's terrific, even when the plotting, which includes a weary old joke involving a disabled loo, lets the side down. And the dialogue is as sharp as ever. "Look mummy," insists Karen, "I used to believe in wishes and all this nonsense but then my wish about Ben and the hyenas didn't come true."

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.