Hello hunky humanists. And good evening all you lovely ladies who know a thing or two about how to get on the right side of a man. Though most of us prefer to be underneath. Talking of underneath, my Alfred nearly dropped off last night. I wouldn't have minded but we had on our new candlewick and I didn't like to risk a spillage. Especially as at the time he just happened to be slurping the last of his prophylactic cocoa. It's meant to be specially fortified to bring out the inner man. But I can tell you it would take more than a few sips of chocolate-flavoured Irn Bru to make mine stand out. Still, if you've got to have troubles they might as well be little ones… Not exactly side-splitting, is it? Well, you had to be there. Or perhaps it's more to do with who's talking. No doubt if I'd been a man in a wig and an aeronautically designed F-cup brassiere, sporting a flouncy feather boa and half a kilo of dripping diamante, you would have been convulsed with guffaws until tears ran down your over-rouged cheeks. And that's just the men.

Drag does the trick every time – if you happen to be British. That's why the Little Britain team, in their tireless quest to mine the seams of national identity, are so obsessed with dressing as women. They've recognised that the hilarity that breaks out every time a jock puts on a frock is so very deeply embedded into our culture and national psyche it should be put on the citizenship test alongside muffins, flat beer, limp salads and cricket.

So it's not surprising that the thespians can't wait for the pantomime season to come round. This year, our most venerable actor, Ian McKellen, returns for another rapturous appearance as Widow Twankey in Aladdin; Clive Rowe graces the Hackney Empire boards as Dame Trot in Jack and the Beanstalk; and Danny la Rue, once described by Bob Hope as "the most glamorous woman in show business", appears in Cinderella as Marlene Dietrich – a bizarre triple transformation in which one gay icon imitates another: a man impersonates a woman who in turn impersonates men.

But what is so nose-fizzingly funny about men in skirts? When Jack's mother berates him for playing with a beanstalk that just grows and grows, when Mother Goose waddles on stage bearing her unfeasible bosom and calling for more bedtime stories, or when the wicked queen in Snow White bends over to reveal a voluminous pair of frilly pantaloons and some saucy suspenders – why does everyone laugh quite so much?

Maybe we're programmed by centuries of habit. Traditionally, the winter solstice was celebrated by the Feast of Fools, when there would be a license to make merry and to poke fun at establishment figures and rituals.

Enid Welsford, in her majestic history, The Fool, describes how in the early centuries of the Christian era the Catholic Church tried to suppress the festivities across Europe, fearing their associations with paganism and devil-worship. In mediaeval France the repeated edicts attempting to ban the Feast of Fools resulted in the emergence of the Sociétés Joyeuses. Bands of carousing young men would dress in motley and create bogus kingdoms led by the Mère Folle – a man dressed as a woman who, for the duration of the feast, would have the authority to campaign for justice and expose wrongdoing, usually through the weapons of lampooning and satire. In particular, the Mère Folle would champion women, denouncing wife beaters and other neglectful husbands.

The figure of the Mere has its roots in a deep ambivalence to the older woman – a mixture of scorn, awe and fear. "Folklore is disturbingly hag-ridden," Laurence Senelick announces cheerfully in The Changing Room, his magnificent tribute to cultural crossdressing. "Recurrent archetypes of ghastly harridans and wicked witches pullulate in the collective unconscious, embodying fears almost too intense for telling, at least among men."

And that's what latter-day crossdressers are doing, too. While appearing to ridicule the weakness of the older woman, they're also puncturing her power.

When men take on her garb and persona they invariably adopt one of two stereotypes: rampant and glamorous, or dowdy and downtrodden. Both represent the worst excesses of female silliness – the very qualities that real women have long ago discarded.

The queen of vulgar, glittering queens has to be Danny la Rue, who burst into London's night club land in the 1950s in stilettos, evening frock, false eyelashes and jokes so louche that he earned the title Danny la Rude. "Hope you'll be a lovely audience, as the flasher said to the girl on the Heath," he'd begin with a wink. Moving from alternative to mainstream, Danny began to dilute the explicit campness of drag with a more palatable sauciness suitable for family viewing on television and, of course, at the pantomime, where he still totters across the tinselled boards each season.

A nastier version of the rampant vamp is Barry Humphreys' monstrous Dame Edna, the Australian housewife superstar, gamely clinging to the last threads of her long-gone sex appeal while brandishing the full regalia of female vanities – and complaints:

My gynaecologist said to me only this morning, Dame Edna, you care more for other people than you do for yourself. And I thought, that's spooky, how can you tell that from a urine specimen? I have a lot of medical checkups, you know. If you are adored by the public as much as I am, you have a responsibility to the public to keep fit as a fiddle. If you're looking for me, honestly I'm running up and down Harley Street with a urine specimen clutched under my mink. Of course it's embarrassing if you bump into someone you know, I always put a few little noodles in it. They think it's bouillon. That's for a sick friend, I say.

The cheaply glamorous, winkingly suggestive older woman, with her uninhibited lusts and dirty laugh, represents all of the sexuality that traditionally has terrified the British man. Contemporary drag artists may claim a more radical inheritance, but they're actually following right in the footsteps of their rhinestone-studded forbears.

Lily Savage, for example, capitalises endlessly on the absurd notion of a sexual woman. "At Eurodisney," she confides, "I had three hotdogs in 48 hours; you can't get nothing to eat." And of her alleged night with Wayne Rooney: "I woke up and saw this spotty forehead, two inches of pubic hair and I thought, Lily you're too old... The poor lad got a rash. I didn't though."

But the glammed-up seduction queen is just one side of the dame coin. The other, equally derisive stereotype is her opposite number – the non-sexual, postmenopausal woman. She's the common, overalled, downtrodden hag as obsessively portrayed by that posh posse of Oxbridge graduates, the Monty Python team. In one of their most adored sketches Mrs Conclusion and Mrs Premise pay a visit to Mrs Sartre and inquire about the health of her old man.

Mrs Sartre: Oh, don't ask. He's in one of his bleeding moods. 'The bourgeoisie this, the bourgeoisie that' – he's like a little child sometimes. I was only telling the Rainiers the other day – course he's always rude to them, only classy friends we've got – I was saying, solidarity with the masses, I said... pie in the sky! Oooh! You're not a Marxist are you Mrs Conclusion?

Mrs Conclusion: No, I'm a Revisionist.

Mrs Sartre: Oh good. I mean, look at this place! I'm at my wits' end. Revolutionary leaflets everywhere. One of these days I'll revolutionary leaflets him. If it wasn't for the goat you couldn't get in here for propaganda.

All the Pythons are really doing with their funny charladies is adding a surreal gloss to a familiar comic figure: the working class harridan, as developed and perfected by a long line of distinguished Victorian music hall comics.

Unlike the university-spawned Pythons, these early crossdressers modelled their female characters on their own experiences. Dan Leno and Herbert Campbell, who for decades held the Drury Lane theatre in thrall in every possible dame role, created their red-nosed, gin-soaked, 'bonnet-and-shawl' shrews from women they would have known from childhood. "The background to my dame is Tucker Street, Watford, where I was born," explains their spiritual descendant Terry Scott. "All the women used to lean on the front gateposts, waiting for their husbands to come home."

One of the best-loved of the 'garden wall' style of crossdresser was Norman Evans, whose monologues launched a whole genre:

Who 'as? Has she? Oooooh! You mean her at number seven. Oh no, I won't say a word, no, I never talk! Well, fancy! Mind you, I'm not a bit surprised. I told her. She would go to them illuminations! And that wasn't the first time. I knew what she was the first time I saw her. Oh yes. That coalman was never away, you know. I mean... don't tell me it takes thirty-five minutes to deliver two bags of nuts! Oh yes. I knew what was goin' on when I saw him shout 'Whoa' to his horse from her bedroom window! Oh, and you know Ethel Higginbottom, don't you? Well, she had her face lifted. It's not safe to leave anything lying about these days, is it?

Norman Evans was Les Dawson's hero, the inspiration for his own much-loved couple Cissie Braithwaite and Ada Sidebottom. Just like Evans, they would speak some words aloud but merely mouth the more intimate ones, repeatedly pushing up their bosoms, pantomime dame style, as they indulged in their garden fence confidences:

Ada: I bumped into May Scattergood and her fancy man.

Cissie: Yes well that one's only as good as she should be.

Ada: Just.

Cissie: So they're on an away day to London too, are they?

Ada: More like a have it away day if I know her. The brazen hussy.

Cissie: Yes, and her husband dead for less than a month.

Ada: I went to the funeral, you know. She couldn't get him in the ground fast enough. It's the first time I've ever seen a coffin arrive in an E-type Jaguar.

Ada and Cissie are the embodiment of the bossy, interfering, disapproving, nosy, curmudgeonly figure who is the butt of Les Dawson's most famous jokes. In other words, they're the mother-in-law – the woman so formidable she cancels her own funeral. She's Mussolini with knickers: the constant persecutor, tormentor and scourge of long-suffering husbands everywhere. No wonder that when she tells Les she's going to dance on his grave, he's delighted: "Good, I'm being buried at sea." No wonder that when he took her to Madame Tussaud's Chamber of Horrors one of the attendants said, "keep her moving sir, we're stock-taking." You always know when the mother-in-law is coming to stay, he confides, because the mice throw themselves on the traps.

Mother-in-law jokes date back to a time when young couples would start their life together in the bride's family home as they saved to afford a place of their own. To many young men, trapped and emasculated by the critical presence of an all-powerful dictator, the mother-in-law as ogre would be a recognisable type. The jokes sprang from terror rather than hatred, just as they did in the mediaeval bacchanalia. And following the same principle, in order to neutralise her power and authority Les actually becomes his own mother-in-law.

What is so beguiling is that Les Dawson and all the other peerless crossdressers are absolute masters of comedy – their delivery and timing are faultless, their scripts fast and brilliantly honed. You can't deny they're funny. But it's a mirth tinged with discomfort, rather like when a goy tells a Jewish joke.

So when Jack's mother stomps on stage in pursuit of her tiny treasure, when Widow Twankey rubs her magic lamp, when Mother Goose complains that her back passage is blocked again, and when all those primped and preened ugly sisters bump their bums together in a parody of female elegance, they're really all just one big mother-in-law standing behind the door with a rolling pin. And your squeals of merriment make you complicit in perpetuating a centuries-old device for keeping women in their place.

But hey – you've got to laugh, haven't you? Where else could you enjoy the spectacle of men flushing with the menopause, chaps getting the curse, boys unhooking their bras – and two great big ones exposing themselves?