A welcome return for the comedy series where the writing and acting are so tight they're in danger of cutting off your blood supply. The least attentive and most dangerous budget airline in the world - tag line: no job is too small but many, many are too difficult - is flying a party of adventurous tourists to the North Pole. Never has a tiredness for life been so malevolent as in the heart and mind of First Officer Richardson, played with sanguine vitriol by Roger Allam. Not known for his love and admiration of Captain Crieff (portrayed with suitably browbeaten desperation by Benedict Cumberbatch), this flight sees Richardson annihilate any morsel of dignity that the Captain had stored away. And, my goodness, is it funny to witness.

Here's a diamond in radio's crown, John Finnemore's comedy about a small airline. He plays Arthur, daft son of Carolyn the doughty owner (Stephanie Cole, funny and sharp here in a role that suits her perfectly, unlike the ghastly one she struggles with in Coronation Street). Roger Allam and Benedict Cumberbatch play (superbly) the first officer and pilot who fly the plane. Today they're off to a little place called Qikigtarjuag, with a party of tourists who want to look at polar bears. Group leader Nancy rubs Carolyn up the wrong way. She'll be sorry!

Bolstered by a breakfast of egg on toast and two glasses of red wine, embittered newspaper columnist Barry Fox sets off for the funeral of his estranged wife, the domineering Andrea, a collage artist whose name was prefixed magnificent "because of her equine physique and teeth". Andrea had ditched Barry and replaced him in the marital home with Nigel, a marathon-running, sex-in-the-morning naturopath (or "onanistic pinko with homespun homilies", depending on your point of view), so Andrea's send-off crackles with jealous recrimination and confrontation. The dialogue is meaty, witty and at times deliciously twisted, with slivers of Latin profundity, and Roger Allam as boozy, belligerent Barry attacks the part with the relish of a lurcher with a rabbit pie. This is Nigel Planer's first original radio drama and it's, well, magnificent.

A wonderful bit of whimsy which included the observation that Helsinki just has to be a brilliant place to visit because it sounds "half helter skelter, half twinkly". "Or," countered the cynical co-pilot (played by Roger Allam of The Thick Of It fame), "like a sink of hell."

Good news: tonight sees the return of Roger Allam as laconic Tory frontbencher Peter Mannion. Mannion's that rare creature - a screen Tory who isn't a frothing monster or a cad. Instead he radiates disdain for the political process, and in particular for his own ludicrous spin maestro Stewart Pearson, a cant-filled creep forever wanting to "take a turn on the ideas carousel" or "imagineer a narrative". Mannion and his team are due at the ministry for a routine visit just as news leaks of problems in Secretary of State Nicola Murray's private life: her daughter is in trouble at school. As always, the rumours spiral into a vicious storm of invective and farce.

Tonight's instalment of officially the best comedy on television (according to me, so there) sees the return of Roger Allam's Tory MP Peter Mannion, last seen in the fantastic specials a couple of years ago. It's a testament to the writing team that Mannion is a likable if fairly impotent character - it would have been easy to portray the Tory as slavering, smug blaggards. It's as sharp as ever, with Mannion's team attempting to capitalise on problems in Nicola Murray's private life. And of course, in the thick of it, there's Malcolm. There's always Malcolm.

This 2007 edition of the black political satire is packed with blood-drawingly sharp observations and ruthless, brilliant dialogue. As well as a lot of laughs. We eavesdrop on Peter Mannion (Roger Allam), a bemused politician who wonders if he's out of step with the modern world. Can he still call yobbos yobbos, for instance? Monstrous spin doctor Malcolm Tucker (Peter Capaldi) and his ferocious sidekick Jamie (Paul Higgins) are back with language that would make a modern rugby league team blush.

Only on radio, where the listener brings the scenery, can a comedy about a small airline take off so successfully. (I'm a devoted fan of that ultra-camp TV show The High Life, but it only had one series.) This has the setting and characters from which classic sitcoms are built: a struggling business, a canny but inexperienced proprietor (Stephanie Cole), her wily chief pilot (Roger Allam), his ambitious young rival (Benedict Cumberbatch) and the good-hearted but daft son of the boss (John Finnemore, who's also the writer). It's really funny.

Welcome return for John Finnemore's situation comedy about a struggling small charter airline. It's blessed with a classy cast, Roger Allam, Benedict Cumberbatch, Stephanie Cole as Carolyn, the boss, and Finnemore himself as her perennially perky son Arthur. And today Alison Steadman arrives as Carolyn's sister. They haven't spoken for years. Arthur hasn't bothered to think about that as he's planned a cheery birthday trip for them all. To Helsinki. He's booked it on his Mum's credit card. And she thought it was proper business.

Krod Mandoon is a spoof, a difficult thing to pull off because the humour is limited to the range of the drama it's sending up. Mandoon is a Dungeons & Dragons fantasy, a bit Robin Hood, a bit Lord of the Rings, a bit Hercules and Xena: Warrior Princess. What it most resembles is a cartoon-like Shrek. It has a good cast and a remarkably generous set and costume budget. It all looks as if it has been performed in some tax-deductible bit of eastern Europe. Everyone turns in a perfectly fine performance, though Kröd himself has the hardest time, being both a hunk and an idiot. Playing a fool isn't the same as being a fool. Then there's Roger Allam, who seems to be going for the TV record for inappropriate casting. At any moment, I expect him to turn up in Hollyoaks.

What kills Krod stone dead before he's out of the first episode, what makes this a long hour of desperate, rictus tedium, is the script. The quick-fire, don't-draw-a-breath, rat-a-tat-tat wit and repartee of this god-awful script is solely and exclusively made up of single entendres about sex. Brilliant juvenile dirty sex talk is one of my favourite things, but this, this woeful, repetitive, telegraphed, winking, prudish smut, was just dire. Here was a great invented fantasy world, full of comic potential, but the script unerringly missed it for the state-of-the-arse joke of least resistance.