Radio: ... so if you want a laugh, go to Bletchley

The Railway Station is dark and chilly; the sad-eyed woman in the bravely jaunty hat gazes up at the handsome doctor she is trying to resist; Rachmaninov billows despairingly around them as an express roars through - and a nerd in an anorak becomes orgasmic as he identifies the train. For this is a brief encounter not with Celia Johnson and Trevor Howard but with the members of the town-council of Bletchley, an adverbial municipality which provides the setting for Julian Dutton's Truly, Madly, Bletchley, the most confident new R4 sitcom since The Navy Lark.

Bathos and soaring ambition are the twin supports of the plot. The town councillors, brassed off with rearranging traffic cones, have opened a public-access radio station and ignited their imaginations. The historical re-enactment society has sent Mr Wilmot off to invade Poland as the starter for their own rerun of the Second World War. And a store detective called Kevin Goodberry is on his way to Palermo challenged, a la Anneka Rice, to infiltrate the Sicilian Mafia. Meanwhile, the church is planning to finance its new roof with displays of naked female mud-wrestlers, joining in the local renaissance with an exuberance which sent me chuckling cheerfully to bed on Wednesday.

But I wish I'd switched off when it ended, for The Cookbook of Apicius (R4) crashes as impressively as Bletchley soars. Keith Floyd is squirmily embarrassing as the Roman chef, discussing skewered dormice with his gay sidekick amidst cumbersome double entendres about the nubility of vestal virgins and the usefulness of pigs' intestines for condoms. Floyd's a passable cook, but no actor: couldn't he just go and make a nice supper for his auntie and leave radio off his CV?

Fact and fiction became further entangled this week when a new genre appeared with Fictuality(R3). We all, of course, know what we were doing when Kennedy was shot, but I remember being in Paris the night Pompidou died. This ability of certain news items to affect our lives is the starting point for this excellent series. Each story centres around a real event as it breaks into the life of the protagonist.

The best I heard was Julie Myerson's "Weekend Break", in which a young couple arrange a short holiday away from their family in Jerusalem. Their romantic idyll is overshadowed by the capturing of a hostage and the appearance of his mother on local television, pleading for his life. The wife's monologue was read by Harriet Walters, as subtly and as beautifully as it was written. A khaki snake winds slowly down a hill, through a landscape straight from the brilliantly coloured pages of her children's Bible; refusing a tout's offer to show her the grave of Maxwell, she escapes from the Holocaust museum before reaching the children's section, her tears fracturing the dazzling light into kaleidoscope patterns ... unforgettable.

Classic Storylines (R4) is back, to blur further the distinction. Peggy Reynolds considered the far-reaching effects on our culture of Defoe's Robinson Crusoe, born of the Odyssey, parent of countless offspring from Lord of the Flies to soft-porn videos. She's really good at this game. Crusoe, she said, is one of those books that we all believe we have read. We recognise the single, unexplained footprint in the sand, and we add our own gloss.

Lucy Irvine, author of Castaway, has tried living it for real. Her experience informs every aspect of her life. It taught her both to enjoy the moment and to plan for tomorrow: after all, when you can still walk to gather firewood, you don't just pick up what's close to hand. You leave that until you're too weak or hungry to move far.

It hadn't occurred to me before hearing this programme that Defoe was in fact posing an elemental question: how would you cope? It lies behind the phenomenal success of Desert Island Discs (R4). We long for the pretty idyll and are repelled by the cruel reality, yet in the cosy context of the BBC and Sunday lunch we dare face it. This week someone who described herself as a jumped-up chorus-girl and an utterly unqualified show-off considered the problem. Irene Thomas - in fact, a charmingly modest compendium of information - chose an enjoyably catholic variety of records and a luxury that epitomised the ragbag of delights which was the late- lamented Round Britain Quiz (I wish they'd revive it). She's taking a teddy-bear stuffed full of teabags, a bottle of perfume at its neck.

The nation's teddy-bear, for several years, was John Betjeman. In Softly Croons the Radiogram (R2), a benign George Melly celebrated the collaboration between the last genuinely popular Poet Laureate and the composer Jim Parker. Parker set three collections of his poems to music, with such sympathy that the settings, once heard, become indispensable (these have been re-issued by Virgin, on their Chattering Classics label). My favourite was "Youth and Age on Beaulieu Water", in which Clemency, the general's daughter, rows strongly into the distance, away from the pining, bald old poet to the quietly comical strains of a melancholy euphonium.

And what are you doing this evening? Will you be beset by the classic British Sunday ennui? Last Sunday made a virtue of inevitability, rejoicing in The Art of Boredom(R3). Boredom is a recent invention, but, none the less, a mighty spur to travel and creativity. Naughtily quoting various crushingly tiresome radio moments, Julia Eisner made a strong case for revelling in dullness, as did the heavenly Mr Pooter. This is what he'd be doing tonight: "I'm always in of an evening: there's always something to be done, a tintack here, a Venetian blind to be straightened there ..." Ah, domestic bliss.