Until four years ago Irish pubs in London were largely to be found in Kilburn or Camden. With Irish landlords and Irish bar staff serving an Irish local population, they didn't advertise themselves as Irish, they just were, with hurling on satellite, traditional music on a Saturday night and Guinness on tap at £1.50 a pint. Now an Irish pub is more likely to mean sepia prints of Yeats and Joyce, rusting Guinness Toucans and framed copies of The Irish Times. "Britain is very good at assimilating other cultures," says Kevin Hayes, a stand-up comic from Waterford who has lived in London for 11 years. "But now it has gone too far. What is being sold is the Irish stereotype in kit form, while the real thing is under risk of extinction."

The "last real Irish pub in Camden," he says, is currently being re-incarnated as an Irish theme pub, one of Scottish Courage's Finnegans Wake chain. It all started gently enough in the late 1980s, he explains, when the atmosphere towards the Irish changed after the freeing of the Birmingham Six and Guildford Four. But then the big boys moved in: first Allied Domecq with Scruffy Murphys (36 in the UK), then Bass Taverns with O'Neill's (now around 100). The consumer director of Bass, Bob Cartwright, is unrepentant. The growth of branded pubs has put life back into a declining industry he says. "O'Neill's are destination pubs, not community pubs. The big trend in the last few years is the recognition that you have to give people a good reason to go out. One of the reasons for going out is food. The other is atmosphere." For atmosphere read music. All theme Irish pubs claim to play exclusively Irish bands, from hardcore traditional to Van Morrison, Thin Lizzy and Dexy's Midnight Runners. Most also offer live music several times a week. "Large numbers of people go over to Ireland and they would like to repeat the experience," explains Cartwright. "It's as if you are having a weekend in Dublin, without having to go there." Dublin is, of course, where Kevin Hayes honed his drinking technique, after qualifying as a civil engineer. That was a career he pursued in England until he turned full-time comic. To an extent his success confirms the pub trade's view that customers need something different. Making a living out of comedy in Dublin would be impossible, he says, because the circuit is so limited.

"It's to do with the fact that there are so many good pubs in Dublin that you don't really need a good comedy club, you can just go to the pub and have a good time in the bar, whereas it is generally quite dull in London. If you don't want to see a band, comedy is a very good choice - a good evening's entertainment." And being Irish, he believes, does him no harm. "Because of the fascination with Irish culture, it's a good time to be an Irish comic. People just want to know; they're really interested. They really like us."

The success of the Irish theme pub - ersatz or no - would tend to confirm that view. Whether it's the bar staff or the music or the mix of people these places attract, the formula clearly works. According to Bob Cartwright, the joint weekly takings of five Bass pubs in south London jumped from £20,000 in the week before Christmas 1994 to £103,000 in 1995 after being given the O'Neill makeover. Although it only opened 18 months ago, Waxy O'Connor's is already a Soho institution and one recent sweaty Thursday evening, Kevin led me passed the bouncers into the gloomy interior heaving with young people. Like all theme Irish pubs, Waxy O'Connor's majors on wood: floors, tables, shop fittings - here a chemist's, there a haberdasher's - even signposts thoughtfully translated into Irish (the village bar, the church bar, the tree room). And it needs them. There are four bars and eight separate rooms, all in the bowels of a Victorian Gothic building fronting Rupert Street, though the labyrinth continues 30 or so yards back to another entrance in Wardour Street.

Waxy O'Connor's is extraordinarily successful: another two are about to open, in Glasgow and on Fifth Avenue, New York, with a further 32 sites already earmarked in the US. It was recently honoured by CAMRA - Britain's pressure group for real ale and a long-time critic of Irish theme pubs - with its Plastic Leprechaun Award. CAMRA doesn't like anything about Irish theme pubs, including their names, many of which they say are demeaning to the Irish. The worst cited example was a plan to open a pub called Beastie O'Shags in Norwich but, mercifully, the authorities turned down permission for the venture. Allied Domecq's spokesperson informed me that its chain, Scruffy Murphy's, was "a colloquial Irish term for a donkey". "It's all part of the plastic Paddy industry," says comedian Kevin Hayes. "The Irish are not very good at drawing their own image. In the 1970s and 1980s we were all murderers. In 1975 it was Stangeways; now it's pubs. They're still trying to put us behind bars."

But at the bar, enjoying their Heineken, fellow ex-pats Aisling O'Connor and Mary McGuinness from Tipperary and Longford see no harm in them. "Other pubs, it's all men in suits standing outside on the pavement," explains Aisling. "You wouldn't wear a suit in Ireland in a pub unless you had just come from a wedding or a funeral. We come here for the atmosphere."

"All the bar staff are Irish," adds Mary. "It's nice to come in and hear the Irish accent - and not `cheers' but `how are you doing?

I'm grand'. It reminds me of home and you can meet other Irish people. You might meet someone you know."