Sex, ladies and gentlemen.

Sex, sex, sex. But why was it so boring? There was certainly plenty of it in Masters Of Sex (Channel 4, Tuesday, 9pm), the new drama about sex research in the 1950s and 1960s. Fit, toned, attractive people were doing it repeatedly, but I kept finding my interest wandering round the room. Was that a genuine 1950s headboard, I wondered? Could I get something like it on eBay?

It made for a very strange experience: a programme about sex, with people having sex in it and even sex in the title. And yet Masters Of Sex was a dull piece of television because nobody made me care about what was going on. It was like a dramatised version of the Ladybird Book Of Sex (if Ladybird had ever chosen to tackle the subject): informative, useful but profoundly unexciting.

And there was something else troubling about the programme. The makers probably thought they were being liberated by getting so many people to get their kit off so many times, but what they really revealed wasn't lots of human flesh - it was television's disturbing attitude to sex and the naked body.

The attitude was most clearly on display when one young couple in Masters Of Sex were having sex after their first date. The camera came in close, like a heavy-breathing mechanical voyeur, and did what the camera always does: it lingered on the naked woman while the man remained largely hidden - probably for the old reason that it is mostly men who are behind cameras directing the action.

That this attitude, this sexism, should come in Masters Of Sex of all programmes is particularly disappointing because William Masters and Virginia Johnson, the real people whose work inspired the drama, were pioneers who set out to change attitudes to sex. And yet here we are, 50 years on: still screwed up, embarrassed and obsessed with women's breasts.

Masters (Michael Sheen) and Virginia Johnson (Lizzy Caplan) were what would now be called sex researchers. They were also slightly odd - Masters, for example, convinced Johnson that having sex with him was part of the research. It was extraordinary that they did that, it was extraordinary that they pushed against the conventions of the time, but once you understand that - which we did in the first few minutes - you need drama, you need to care about the characters and what's happening to them.

And despite another interesting performance from Michael Sheen, I couldn't care about the characters. Sheen may be keen to play down his transformative skills (playing Tony Blair and David Frost among others) in an ordinary part, but it means his portrayal of Masters feels terribly pale. Maybe that's the joke of this series - a grey, dull man researching all these beautiful people having sex - but it means our interest is unlikely to endure. The titillation might get us through a few minutes here and there but Masters Of Sex is 12 episodes long - too long, I suspect, for even the most persistent voyeur.