The first episode of brand new Channel 4 sitcom London Irish opened and closed with the four twentysomething Northern Irish expat protagonists getting bladdered in the pub. That's right, writer Lisa McGee (a Londonderry woman herself) isn't afraid to confront those national stereotypes head on. This would also explain the scene riffing on a certain budget airline's baggage policy, and the cameo from Father Ted's Ardal O'Hanlon.

It was sweet of Mr O'Hanlon to bestow on this fledgling show the blessing of the Irish sitcom elders, but if the ultimate aim was to fool us into thinking London Irish owes something to Graham Linehan and Arthur Matthew's work, the ruse failed. As with any sitcom about a mixed-gender group of twentysomethings made at any time since 1994, it's to Friends that London Irish must pay reluctant tribute.

This weight of influence bears down heaviest of all on Kat Reagan, whose character Niamh is a mildly irritating kook in the tradition of Phoebe Buffay. Television doesn't need any more mildly irritating kooks - Zooey Deschanel in E4's New Girl has seen to that - so the angry, sweary, pathologically stingy Bronagh (Sinéad Keenan) was a particularly welcome foil. Ostensibly, there were also two male leads, the garrulous Packy (Peter Campion) and childlike dreamer Conor, but McGee's script betrays her obvious preference for writing female characters and they barely got a look in.

It may be unchivalrous to note it, but, at 35, Keenan is knocking on a bit for a role as studenty as this. It's testament to her energy and talent, then, that her performance was so enjoyable, regardless. Bronagh's righteous indignation at the one-handed man who failed to inform her of his missing appendage before they had a drunken "ride" at a party was easily the best thing in this opening episode.

It's also the strongest hint that McGee's writing might be ballsy enough to eventually transcend the over-familiar setup. If you must make yet another sitcom about the messy social lives of twentysomethings, the Nineties institution on which to model it is not mushy Friends but misanthropic Seinfeld. Might the characters of London Irish all turn out to be shallow, sex-obsessed reprobates with no moral compass to speak of? We can but hope.

Over on Channel 4, rather later after the watershed for reasons that became quickly obvious, London Irish (***) started another six-week residency. The sitcom, about four Northern Irish twentysomethings living in the UK capital, is created and written by Derryite Lisa McGee. The foursome are sister and brother Bronagh (Sinead Keenan) and Conor (Kerr Logan), who share a flat with Packy (Peter Campion) and Niamh (Kat Reagan). Packy is a slacker, Niamh is a nympho, and has a jailbird boyfriend who bores her but whom she keeps in contact with "for a ride", while Bronagh has range of fruity insults for her dim brother, including "dickswab" and "fucktard".

They are part of a generation mercifully untouched by terrorism, so instead of brooding about the stereotypes of politics, religion and history, they can get on with living up to the, er, stereotypes of drinking too much, having lots of sex and and swearing like navvies. I think there's a joke in there somewhere, but McGee doesn't upend the tired tropes to make them funny.

Last night's story concerned Packy bumping into Ryan (Ciaran Nolan) from back home, who lost his hand while covering a shift in a garage for him, when he was shot in a hold-up. Packy organises a charity quiz - "like an exam in a pub" - at the foursome's local to raise funds for Ryan's new robotic hand. Cue lots of rather weak jokes about not him being able to clap or going to a fancy-dress party as Captain Hook - Peter Cook and Dudley Moore's one-legged actor auditioning for Tarzan it was most definitely not.

The opener was a bit frantic and unfocused, and the actors are all a little too shouty - always a bad sign in a comedy - and, despite some smart lines and the welcome presence of Ardal O'Hanlon as Bronagh and Conor's Da back home, it will have to improve swiftly to gain a dedicated following.