RADIO / How to take the situation in hand: Talk is expensive: Robert Hanks opens up about sex and greets Alan Partridge in his new role as chat-show host in Knowing Me, Knowing You

'It's only recently that I tell people that I masturbate,' one woman confessed on Talk About Sex (Radio 1, Wednesday), and you had to be impressed by the way she'd come on - already chatting openly about it on national radio as though this were the most natural thing in the world. Still, her admission raised a number of questions, among them: how do you set about telling people? Do you wait for a convenient conversational lull and then plunge in boldly ('There's something I think you ought to know . .

. ')? Or is it better to wait for the conversation to drift round to masturbation and then drop your bombshell casually ('. . . Speaking of which, I do a bit of it myself')? But the main question is, why tell anybody at all? Unless they ask, of course.

It should be said at the outset that Talk About Sex, a three-part series looking at 'sex and sexuality in the Nineties', is a highly responsible and serious- minded enterprise. Its half-hour of testimony to the varieties of sexual experience rolls on, punctuated by announcements about the confidential One FM sex talkline, without a hint of a snigger or a double entendre. You can imagine the intended audience - worried teenagers sitting in their bedrooms, listening over their homework, and feeling relieved to find that they aren't alone in their anxieties. And you couldn't accuse it of overselling sex, with its long line of young people talking about the pain and the embarrassment they had gone through to lose their virginity.

The problem with the first part was that it sank under the weight of its own worthiness. You could feel it ticking off the issues as it went on - Masturbation: check. Loss of virginity: check. Male homosexuality: check. Lesbianism: check. Bisexuality: check. To be fair, this reflected the programme's moral agenda - a generous, inclusive morality summed up by one of the songs on the relentless soundtrack, 'It's OK to feel good.' Whatever you want to do is all right, it's normal. But, leaving aside the fact that there are two sizeable minorities over whose needs the programme rode rough-shod, the highly inhibited and the completely unsuccessful, it still felt perfunctory, and finally tedious.

Meanwhile Alan Partridge, host of Radio 4's controversial new chat-show Knowing Me, Knowing You (Tuesday), treads on the toes of practically every minority you can think of; as a result, the programme caught the sharp side of the listeners' tongue on this week's Feedback (Radio 4, Friday), which this week featured several complaints about its puerility and unnecessary explicitness; this probably cheered its makers up no end.

Knowing Me, Knowing You is a spin-off from the excellent On the Hour, Knots Landing to its Dallas. As that image should suggest to the teleliterate, it has some of the characteristics of its parent programme, but doesn't quite live up to it. To begin with, it has inhospitable subject matter. On the Hour, being a spoof of news-programmes, could pull in a lot of disparate material, and could be made in isolation, so that it never lost its poker face. But the chat- show, the target of Knowing Me, Knowing You, is a far more restrictive form. In particular, a chat-show has to have a studio audience to applaud the guests, laugh at the jokes, generally lend proceedings a bit of ambience. Unfortunately, the audience here never stops laughing, so that the joke has been exploded by the studio audience before it reaches the listener. The only way the programme could really work, in fact, is to have an audience consisting entirely of skilled comic improvisers, who could keep a straight face throughout. Failing that, you could try to get an audience entirely devoid of any sense of humour.

Still, the programme has effectively punctured some chat-show conventions. There are knowing squibs about the fake knowledgeability of chat-show hosts: Partridge gets a guest's name wrong, and says sorry, 'but I'd never heard of you before tonight'. He begins a question by saying, 'Now I read a bit in your book that was highlighted in yellow by a researcher for me . . . '

It's hard to know where it goes from here. Steve Coogan's characterisation of Partridge, a self-proclaimed 'Argos / World of Leather man', with his ersatz man-of-the-world philosophising ('Maybe O levels and A levels are just bits of paper . . . that you have framed in your office'), is brilliant, and never cracks. He's a driver you can rely on; he may need a different vehicle.