Yet despite his obvious mental and physical deficiencies, the ubiquitous comic Irishman has enjoyed huge international popularity, gate-crashing four centuries of English theatre history in the guise of various roguish soldiers, poachers, sailors, beggars and bawds. He was Queen Victoria's favourite stage creation and indeed - thanks to Dion Boucicault's The Shaughraun - the last she ever saw.
But it was Shakespeare who first exploited the stereotype with the doltish, temperamental Captain Macmorris in Henry V. After this, every farce or low comedy boasted its resident Paddy or Teague until Sheridan, in The Rivals of 1775, added a new dimension with his portrait of Sir Lucius O'Trigger, a comic character of comparative warmth and dignity: "I was only taking a nap at the Parade-Coffee-House," he tells a young companion whom he had planned to meet, "and I chose the window on purpose so that I might not miss you."
Then came the Victorian Melodrama, the gobshite Golden Age of the Stage Irishman. Impudent, divil-may-care oafs wandered through the sumptuous 19th-century scenic effects, answering to names like Thady MacBrogue or Wild Murtough, spouting malapropisms and as often as not bailing out the plot in the end: a moron ex machina.
Finally a saviour arrived in the Franco-Irish Boucicault, himself something of a stage rogue: thrice-married (once bigamously) and a spendthrift who lost three fortunes. His spectacular, melodramatic plays, like The Colleen Bawn, The Shaughraun and The Streets of Dublin, elevated the stage Irishman from comic turn to the position of mouthy, transgressive anti-hero - the basis for much of this century's Irish literature, Wilde, Synge, O'Casey, Joyce and Beckett included.
"What's that on your shoulder?" asks a prying magistrate of the Irish smuggler Myles Na Copalleen in The Colleen Bawn. "It's a boulster belongin' to my mother's feather bed." "Stuffed with whisky?" continues the magistrate. "How would I know what it was stuffed with," says Myles. "I'm not an upholsterer."
But the comic Irishman was more than just a device, he was the very antithesis of Englishness: where John Bull was male, aggressive, commanding, Eire was femine, weak and irrational.
The Stage Irishman was also a sensitive gauge of Imperialist British prejudice and hostility. His fortunes have always been inextricably linked to Anglo-Irish relations: when they were favourable, his IQ leapt almost into triple figures; but in times of turmoil, the encephalogram was practically blank. A period of relative calm in the 18th century was rewarded with Sheridan's gentle caricatures. But less than 100 years later, when the famine-devastated Irish were pressing for independence, it was business as usual for Pat, Paddy and Teague.
Thus, the Stage Irishman functioned as part of an ideological strategy: to show the conquered race as docile, foolish, impetuous, dense, childlike, bestial, and incapable of self-rule. The settlers would do the same to the natives of North America. And practically everyone would practise the technique on the races of Africa.
But this century has seen something of a turnabout: the revenge of the Stage Irishman. The irreverent, lippy, roguish outsider - pretty much as Boucicault left him on his death in 1890 - proved to be the ideal base for modern Irish drama and literature. Once he had perfected his "brogue" - the word, meaning "shoe", refers to the way the Irish mouthed their new, enforced tongue as if they were chewing on leather - the wily Stage Irishman could slip into the castle and take his master's place. Shaw built on Boucicault - stealing the trial scene from Arrah-na-Pogue lock, stock and gavel for The Devil's Disciple. And even Wilde borrowed some of his wit: when a character in The London Assurance reveals that he is in love, "How?" asks his friend. "Vulgarly, with a woman - or fashionably, with yourself."
O'Casey (in The Plough and the Stars) and Synge (in The Playboy of the Western World) broached the Hibernian hinterland to explore the roots of the Stage Irishman and found characters far more brutal, self-deluding, complex and viciously absurd than any English playwright could dream up. The exercise was so successful that Irish audiences rioted when they saw the results, accustomed to seeing themselves only in the familiar, less threatening stereotypes. Brendan Behan liked the role so much, he not only gave it to all his characters, he took it on himself.
Most curious of all is that, while the more extreme, thick-headed manifestations of Stage Irishness have, thankfully, disappeared, the dynamic of four centuries remains immaculately preserved. Irish dramas currently celebrated in England fall into a familiar category: verbal, apolitical, romantic and feminine. The superlative plays of Billy Roche and the works of Sebastian Barry (whose idiom is far more "oirish" than the hype would admit) fit the description with uncanny ease. Perhaps this allows English critics, as it has done in the past, to praise and condescend at the same time. Perhaps this is just a more authentic, resonant, archetypal portrayal of Irishness. Or perhaps, like Old Mahon, beaten and insensate at the end of The Playboy, the Stage Irishman is the "corpse" that refuses to lie down quietly and die.
n 'The Streets of Dublin' is at the Brixton Shaw Theatre 7.30pm, to 20 Jan. Booking: 0171-274 6470