"Lynne Turner is 33." The presenter's first sentence is a classic of its kind, a simple fact delivered in a clear and positive voice. Aha, we might be expected to think: a slice of life here; a fly-on-the-wall documentary; a warts-and-all portrait of contemporary society; a frank expose of modern manners; a cliche, in fact, of investigative radio journalism.

But those of us who have already recognised the voice of Chris Langham as Roy Mallard, this voice with its tiny hint of self-doubt - no more than a speck of yolk amidst the smooth blandness of the whites which, nevertheless, presages the ultimate doom of the meringue - are happy. We have rushed to take the phone off the hook and locked the door, determined that nothing will interrupt what follows: the first of a new series of People Like Us (R4).

Our delight is not simply schadenfreude. There may be an element of sadistic pleasure in witnessing Roy's extravagant failure to share an ordinary day with somebody doing an ordinary job, but there is far more to it than that. The slightly overblown meringue sentence in the previous paragraph is proof of the Mallard effect. His firmly suppressed nervousness results in ludicrous over- compensation, and it's as infectious as chicken pox.

This week, his subject was the Mother. But the chosen mother, Lynne Turner, had twins: grammatical anxieties caused by this doubling began in the second sentence. "She and her husband have been married for a total of eight years between them," said Roy. Then, drawing attention to his problem while trying to disguise it, he added, firmly, "Obviously". And ploughed on. "But, last year, their lives were changed irrevocably by the arrival of Rosie and Ben, twin ..." (oh dear, how to finish this sentence? Of course: firmly again) "... twins".

Within moments, Lynne had caught it. Asked their age, she replied "They're both 11 months each". The writer, John Morton, doesn't overplay this conceit but revives it with variations throughout the ghastly day. The main joke, as usual, is the character of Mallard. Serious, well- intentioned, infuriating, he accompanies his victim, making her busy day infinitely worse by a maddening mixture of incompetence and bad luck - breaking her washing machine, fainting as a baby is vaccinated, managing to lose an indispensable toy. And behind him, Lynne's own mother demonstrates by her bossy interference just how frightful the Mother can be. Eventually, the saintly Lynne rounds on Mallard, as we know she must, and screams at him to go away. Undaunted, he'll be back next Saturday morning.

A real fly-on-the-wall documentary, Cheshire Wives (R4), is in fact a different kind of spoof, sending up the Hollywood-style aspirations of a group of rich women who live behind electric gates and alarmed windows in the leafy outer reaches of Manchester. Yet this too is a subtle, beautifully made series and very funny, in an appalling kind of way.

The first programme eavesdropped on the charity lunches that occupy so much of their time. Undoubtedly these affairs generate some useful cash for worthy causes, but, oh heavens, the bribes devised to make them part with the dosh ... designer everything, from belts and key-rings to hair- dos and face-lifts, for appearance is very nearly all to these women. This week, we went to Ladies Day at Chester Races, where the main objective is to be photographed for Cheshire Life, the local equivalent of Hello!.

They talked about their taste for champagne and "Louis Quinze" brandy: it's pounds l,200 a bottle but worth it, because it's nice, like Versace jeans (how they must mourn the king of glitz). They boasted of the cherished number plates on their Porsches (oh yes, that's quite normal in Alderley Edge), of their holidays in Mauritius (with no less a celebrity than Cilla Black next door) , of helipads and of hats. One described with relish her pink topper, wider than her shoulders and bedecked with hand-made sunflowers and yellow ostrich feathers down to below the waist. Cheshire Life would be mad to miss a photo of that - wonder if they do out-of-county deliveries?

Lindsay Leonard produced a series that was admirably non-judgmental, and the reporter, Clare Jenkins, elicited enough rare introspection from these preposterously spoilt creatures to leave you marvelling at the vacuity of it all - and, in my case at least, very glad indeed not to be confronted with the exhausting problem of how to get through a vast fortune every day or two. Honestly. I mean I don't think I'd even like Louis XV brandy. Besides, as one of them let slip, "Somebody said to me - I think it was a workman - that around here it's all fur coats and no knickers".

As I sit here writing this, the Governors of the BBC, in what we can only hope is their wisdom, are pondering the widely-leaked Boyle proposals for the reform of R4. Un- doubtedly these suggestions will provoke enormous controversy. At this stage, I'd just like to draw their attention to some of the excellent programming that must be encouraged to continue on this important network: the splendid comedy, the instructive documentary and the final witness for the defence - the interviews.

In Just the Part Rodney Milnes talks to opera singers about the particular roles that they have made their own. Tom Allen struggles with Don Giovanni: at the beginning, he said - alarmingly - that the lascivious roue is "a distillation of all of us" - adding, as if by way of explanation, "there are no moors in him". Sorry, what? Maws, mores, Moors?

But when he got going, he was terrific at describing the seductive charm of the villain, the immense vitality of a man who knows no fear, who would, if the earth were flat, crawl on his hands and knees to the get to the edge and look over at the other side: no fear, that is, until his last terrified - and terrifying - cry as he is swept away to perdition.

The conversation was littered with snatches of Allen's own superb recording of the Don's best bits. As Milnes sighed, the pity is that sin has so much grace. Dear governors, do be sure to leave room for programmes like these.