When - 20 years ago - Mrs Slocombe informed her co-workers at Grace Brothers' department store that she had been caught in a storm and that "the rain played havoc with my pussy," what was she really telling us? On the one hand it was hardly credible that a very straight-laced woman of a certain age would want to discuss how her genitals had got wet. On the other, what on earth does it mean to say that your moggy has been "played havoc" with? No literal interpretation of this gag could possibly explain its effectiveness.

Last night, in Has Anyone Seen My Pussy? (Channel 4), we were invited to explore the strange world of the double entendre - once the mainstay of British sitcoms. Introduced by Julian Clary - showing off a few of his own favourite plum and banana jokes - the show cantered around the genre, stopping occasionally to make an important point.

As it suggested, if one side of the double entendre - the funny side - is taken literally, it is unbelievably filthy. "Your sausage is bigger than mine," Reg Varney says to his colleague in a clip from On the Buses. "Let me measure it. Look! It' s bent!" The mistaken phrase must read, "your penis is bigger than mine. Let me measure it. Look! It' s bent!" The other interpretation is simply banal.

But this, like the Slocombe case, is puzzling; Reg Varney has no interest whatsoever in the other chap's todger. So what is going on? The fashionable explanation is, of course, that in a more inhibited age this stuff about sausages, pussies and a bit of the other allowed comic writers to talk about taboo subjects. If you couldn't actually say penis, you could say sausage.

Then the double entendre died because sex became widely and frankly talked about; as in Men Behaving Badly , or a scene shown from the brutish Game On, in which a character finding a couple in bed asks, "Have you two bastards been shagging?" But I wonder whether the studio laugh that this line mystifyingly received was really any different from the guffaw for "Let me measure your sausage"? Surely, some folks just like it crude.

But then I am probably very "PC". A chap called John Thomson - appropriately shot against a backdrop of a soft, wrinkled sculpture which looked like a flaccid cascade of large, lollopy willies (a deliberate case of double voir) - told us that the young were now turning back to these old sitcoms (buying newly released videos for their parties) as "a revolt against PC". In my experience revolts against PC usually mean silly, drunken young men making jokes about tits, with the rest of humanity forced to listen for fear of being thought stuffy. No, John, I think they are turning to On the Buses because they are thick. In due course David Blunkett will deal with them.

Having said that, I have my thick moments too. My own favourite show from the 1970s was Up Pompeii, in which a gay man (Frankie Howerd) played a voracious (if camp) heterosexual slave. Many of the jokes were about breasts. In Tickled Pink (Channel 4, Saturday), a slow American documentary about gay writers and characters in US sitcoms, one chap spoke (I think ironically) of how he too was now confident enough to write sexist gags about breasts, despite the fact that he knew nothing about them. This, apparently, was liberation.

True liberation is to be found in programmes like It's Not Unusual (BBC2, Sunday), the first in an excellent, conventionally made oral history of British homosexuality in the 20th century. What a delight (often tinged with sadness and anger) it was to hear the testimony of elderly homos about the age before queers became gays (let alone the age before they went back to being queer).

Perhaps most interesting was the fear of new intolerance felt by the previously tolerated monocled lesbians of the early 1930s, when Radclyffe Hall published The Well of Loneliness. Hall's courage prompted the Editor of the Daily Mail to write that he "would rather give a healthy boy or girl a phial of prussic acid than this novel". Plus ca change, eh?

I also wondered whether the heartily recalled "school tart, a boy called Richmond" (now presumably in his early seventies) was still alive, and if so, what his watching grandchildren, if any, made of this description. "Grandpa," they may have asked, "what did a school tart actually do?" And what about all those still photos of nude boys? If they'd turned up at Boots, we'd be looking at someone doing a long stretch in chokey.

The most wonderful tale was that of wartime pilot Chris Gotch, who returned to his room one evening to find his ranking officer waiting for him. Instead of discussing the next day's mission and the progress of the war, he recalled, "the Wing Commander leant over and gave me a great big kiss". Then it was a case of roger and out.

At the same time, on the two big channels the search went on to find the Sunday night successor to Dr Finlay. Wokenwell (ITV, Sunday) is set - like Dad' s Army - in a mythical small town where every male has a trade. There are three policemen, a butcher and undertaker, a teacher and so on. I will reserve my opinion about this series for a few weeks, though it shows horrid signs of being whimsical. But it is based on the truth that smaller communities make for cosier Sunday dramas. Wokenwell is set in a small northern town, Ballykissangel in rural Ireland, Hamish Macbeth in a Highland fishing village. But Plotlands (BBC1, Sunday), went a step further, locating the action in an empty field; a wet empty field, somewhere in Britain after the Great War.

To this unappealing patch of dock leaves and dandelions comes a young woman and her two daughters, escaping an abusive husband. Having purchased a thistle patch, they are forced to live in a white tent. Around them others are building log cabins.

Fortunately the woman is played by Saskia Reeves, an actress who looks lovely when soaked. Reeves - one of the few actresses who seems to have a normal person' s voice - is good on suffering and redemption; rays of hope pass across her face, illuminating her eyes and setting off small, barely controllable smiles.

This week, struggling on her plot she eats green potatoes, falls horribly ill, encounters kindness and starts to fall in love with the husky plotholder in the next shack. Episode one ended with her first fence going up around her, and small, barely controllable smiles seizing her lips.

This classic storyline (mysterious background, troubled times, starting anew, fallen low, gradually rising again, new love) is immensely satisfying. And how good it is to discover that someone in BBC drama knows how to film in the rain.

Such a brave act of television minimalism (the set must have taken about an hour to erect) is in stark contrast to the lush and beautifully recreated 1897 scenes in Bramwell (ITV, Monday). This is a series about a woman doctor, her vocation and her loves. Half of it is set in her little hospital, and the other half in damp rookeries where pale, faithful, constantly nursing mothers sew buttons for a pittance, constantly in fear that their drunken menfolk (invariably sporting unpleasant facial smudges) are going to growl about their "rights" and beat the bejasus out of them. There' s loads of blood, early sutures and strong characters.

That was pleasure, now duty. This week everyone's talking about the kids' show Teletubbies (BBC1). Those who hate it are nostalgic for something called Playdays, which - though my family must have tuned into it for years - left less impression upon me and the girls than Teletubbies did in one showing.

Why? Because the T-ts are the Spice Girls for the under-fives; each cutesy blob is slightly different in colour and in the shape of whatever it is that grows from its head. Before the next election someone from the Spectator is going to discover that the Teletubbies intend to vote for William Hague.

I do not find it as compelling as, say, Melissa. But then I am 42 and prefer Crosby, Stills, Nash and Young to Sporty, Scary, Baby, Dopey and Ginger - let alone to Tinky Winky, Laa Laa, Dipsy and Hague. But the thing is, my four-year-old (and a genius, naturally) really likes it. When she is grown up, I hope she will watch more intelligent stuff, featuring middle- aged women who get their cats and their vaginas mixed up.