In one of their funniest sketches, Ronnie Barker and Ronnie Corbett are dressed as Kenneth McKellar and Moira Anderson, singing a jaunty music-hall number about being a famous double act. Performing a dainty two-step between each verse, they managed to combine the louche appeal of a drag act with a sense of glee at the hilarious absurdity of their impersonation.

"Well, we're not John and Yoko, and we're not Bill and Ben," they chorus to a camp little tune which sounds as though it was written by Gilbert and Sullivan, "Marks and Spencer isn't our name, we're Moira and Ken!" For one of Britain's most famous double acts to impersonate another famous double act, singing about the celebrity of double acts, has all the logic of the plot of a post-modern novel.

The layers of parody and punning become increasingly entwined, positioning the Two Ronnies in that grand tradition of comedy duos who play, primarily, on our perception of their relationship. Safe in the mainstream of British television comedy from 1971 to 1986, the Two Ronnies described a Britain of nervous bridegrooms and grumpy plumbers, but could satirise almost anything by simply placing it within the comic world which their names had come to define. To this end, during the height of New Romanticism in the early 80s, they performed a number in which Ronnie Barker was dressed as Kid Creole and Ronnie Corbett was made up as Boy George.

Another shuffle of their creative intentions and they could have done it at the Institute of Contemporary Arts. But what with Ronnie Barker's multi-coloured blazers and Ronnie Corbett's pink cardigans, the Two Ronnies seemed to come from an age before irony, from the era of saucy postcards (Barker, in fact, owns 55,000 saucy postcards) when social caricature was played without conceptual spin.

Towards the end of the 80s, Vic Reeves and Bob Mortimer reinvented the double act, creating a notion of comedy in which being dressed as Kenneth McKellar and Moira Anderson was still OK, providing they were performing a song by T Rex or the Human League. The comedy was derived from a new way of juxtaposing opposites ("What's on the end of the stick, Vic?"), in a way which didn't have to make any sense at all to be funny. The Two Ronnies delivered a comic world which was uncompromisingly suburban - a known, comforting world - while Ronnie Barker, individually, was drawn to slightly experimental projects such as His Lordship Entertains - which has parallels with the late Vivian Stanshall's comedy of aristocratic decrepitude, Rawlinson's End. Indeed, Barker's fascination with English social types led to the brilliantly realised characters he went on to create for TV Porridge and Open All Hours.

But within the Two Ronnies, he dreaded having to play himself. In Bob McCabe's biography of Ronnie Barker, Corbett explains how Barker had to invent a character who was Ronnie Barker: "Once he found a way of doing it, like an actor, it remained the same more or less each night. I would see him remembering to put his hand in his pocket at a certain time and so on. On his own admission, he can't go and open a fete or something because he doesn't know who to be." This hugely empathic relationship with character also won con tinued admiration - and offers of work - from Sir Peter Hall, the former director of the National Theatre, who said of Barker: "His scripts are very precise. I think the writer and the actor kind of coalesce in their precision, because although he's an anarchic comedian in some respects, as a performer he's about precision." In terms of television comedy, that was pre-ironic anarchy.

Now, 11 years after their last show together, the Two Ronnies are being given their place in the cathedral of light entertainment. With tributes from John Cleese, Ben Elton and Neil Morrissey, the duo are receiving the televisual equivalent of canonisation in the forthcoming Two Ronnies theme night, on BBC1 on July 16, and a BBC Comedy Greats video is due in the autumn. Described by Ron nie Corbett as "a scrapbook of our lives together", the theme night is a retrospective celebration of the duo's achievements. But Corbett's phrase, "our lives together", seems to touch on a common denominator of double acts within a broader cultural tradition.

Best exemplified by the sexless yet cosy manner in which Morecambe and Wise shared not only a bedroom, but also a bed, there is a soft core of domesticity at the heart of most double acts - particularly when the odd couple in question are the same sex. Within the supposed domesticity of their relationship, a double act can present life together to the audi ence as the basis of their comedy.

The Two Ronnies made far less of this than Morecambe and Wise, preferring to play characters than suggest that their real selves were living in the world of their comedy. But the notion of a comedy duo sharing a bit of their world with the audience was picked up by Vic Reeves and Bob Mortimer, who played on the supposedly domestic relationship between themselves as a mutually dependent but frequently arguing couple.

For Morecambe and Wise, there was never any question that there might be sexual ambiguity in the domestic world that they presented. From kitchen to bedroom and back again, Eric and Ernie based an entire comic formula on the idea that we got to see how they lived when they weren't actually on the stage.

It was like the Beatles' house in Help! all over again. And in their autobiography, There's No Answer To That!, Ernie Wise gets straight to the point: "The great thing is to be able to do sketches in that flat without anybody having any ideas that we might be queer. We even used to share a double bed at times, but no one has ever suggested that there was anything immoral in it."

Questions of morality to one side, however, Eric Morecambe recounts how the BBC was sensitive to the ambiguity of the double bed, even if its occupants were not: "I always smoked a pipe in the bed for the masculinity. I'll tap him on the head with it. But the hierarchy at the BBC once said: 'You can't get into bed together You have to have two separate beds.' But we thought that would have made it worse. In fact, we never had a single letter of complaint. Nobody else could do that. Little and Large couldn't. In any case, I think we've made it our own domain now."

The founding examples of a same-sex double act, living together in the universe of their own comedy, are the eponymous heroes of Flaubert's last great novel, Bouvard and Pecuchet, which was published a year after Flaubert's death, in 1881. The story of two disaffected office workers, released by a sudden legacy to pursue their quest for total philosophical knowledge, Bouvard and Pecuchet set a model for comic couples which has its contemporary equivalent in the cartoon, Ren and Stimpy. Just like Ren and Stimpy - the bad-tempered chihuahua and his doting friend, the goofy cat - Bouvard and Pecuchet live together in their own bizarre house, preyed on by society, and are continually thwarted in their attempts to find happiness by the limits of their own intelligence.

In a single line, Flaubert explains the relationship between Bouvard and Pecuchet: "The friendship between them was profound and absolute." There is neither sexual ambiguity nor distracting sentimentality, so this comic universe can be presented ready-made. And this comedy is maintained by the manner in which the heroes become comic victims, retaining our sympathy because much of what they endure is due to the stupidity of a bigoted and complacent society.

Culturally, we can use the double act to become mirrors of society and social change. We observe the double act as pioneers setting off into the wilderness of fate and circumstances. They seem to demonstrate our collective vulnerability to the temper of the times, primarily through struggle and suffering made palatable by comedy. Laurel and Hardy, for example, become the victims of bad-tempered bosses and bullies, as much as the victims of their own incompetence, and their struggle was usually to find a lucky break in the midst of depression or poverty.

For Bouvard and Pecuchet, the search for happiness ends when they decide to become office clerks again. And as for Ren and Stimpy, their mantra of "Happy, happy, joy, joy" is arguably one the the saddest lines ever written. But what happens when the potential of the double act is extended beyond comedy, into other areas? In the art of Jane and Louise Wilson, as twins who work together as one artist, there is a sense that the viewer is witnessing an experience of detachment and solidarity. But the authority of this vision is heightened, to some extent, by the fact that it has been created by two people working as one.

There is the strong sense that we are seeing a glimpse of Wilson World, particularly in the pieces which feature the twins themselves. For their installation, Hypnotic, Suggestion 505, the twins were filmed being hypnotised in matching office chairs, against what looks like a blue-screen backdrop - two young women, trusting to the power of suggestion. More disturbing l, they have photographed themselves in what looks like the preparation for a suicide pact, with one twin wearing a noose while the other lowers her head into a tank of water.

As with The World of Gilbert & George, the stage shows and videos of the Pet Shop Boys, or even Jake and Dinos Chapman's Chapmanland, that double acts who work within the broader arena of contemporary culture are usually presenting an idea of survival from a position of isolation and melancholy. In the most famous double act of the grunge generation, Beavis and Butt-head, there is the overriding impression that their boredom and nihilism is the result of living in a junk civilisation, ruled by bad rock videos and peopled by corrupt sophists.

What the double bed was to Morecambe and Wise, and the news desk to The Two Ronnies, so Beavis and Butt-head's tele-vision is the centre of their comic universe, and the label of their domestic relationship. Stage- diving off their smelly sofa, Beavis and Butt-head occupy a limitless suburbia which is so dull that when their television finally breaks, they can think of nothing better to do than throw a dustbin at one another. A more potent symbol of the power of the double act would be hard to find: in the end, they have nothing to lose but each other.