THEATRE Cardiff East RNT, London

It's called the Royal National Theatre of Great Britain and Northern Ireland, but apart from the odd revival of Under Milk Wood, it's hard to remember the last time the Welsh got much of a look-in on the stages of this institution. Did I hear you say, "Honey, count your blessings"? Shame on you.

The balance is redressed now with Cardiff East, written and directed by Peter Gill. With 14 actors on a mostly bare set, the play interweaves the voices and the stories of a white, working-class community in a part of Cardiff that could be worlds away from the shiny enterprise zone of the Bay. Alcoholism, unemployment, gambling, drugs and disintegrating families feature prominently in the picture of the city's deprived proletarian culture that is built up here.

One young man has drunk away all his redundancy money and takes out his self-hate on his wife. He's in a double bind: numb with hopelessness if he doesn't indulge and a hopeless case if he does. As his distraught wife screams, "You know there's more to you and then you have to go and drink to feel it." Elsewhere, an embittered woman, abandoned by her husband for a younger woman and second family, drives her drug-dealing son to the end of his tether with her guilt-ridden possessiveness. The death in the past of another of her sons murkily links this household to two youths who can't as yet quite acknowledge that they are having a homosexual relationship.

Gill, you guess, knows these people intimately and has a keen ear for the gossipy rhythms of their compulsive reminiscing and conversation, whether they be discussing plants ("Next door, she's got a clever idea, she mixes lovely artificial flowers with her other flowers, you wouldn't know") or feminism ("I hear these women on the telly; they don't want much do they?") or teenage pregnancy ("Girls don't get pregnant to get flats, Dolly, they're too stupid"). All these quotes are from women.

If it weren't for the fact that it's hard to cotton on to all the complicated relationships in the large cast, this is a play that would lose very little on radio. And, though the blurb on the script talks of the play building "towards an inexorable climax", both the final events could have happened plausibly at any time in the second half.

The question of national and cultural identity that preoccupies the piece is addressed most directly by Kenneth Cranham's moving Michael, a fiftysomething idealist who trained for the Roman Catholic priesthood but lost his faith in North America. It's there he saw that what he thought was a universal church was simply "Ireland, cruel, sentimental, stupid". With this came the realisation that, throughout his Catholic boyhood in Wales, a sort of "inverse imperialism" had allowed "foreign bullies" to make him feel Irish and "to genuflect to a notion of someone else's nationalism".

At one point, the cast mill about spouting lines in Welsh and in all the other immigrant languages heard in Cardiff. Michael stops them, saying, "Why don't you speak in English?" From the perspective he has arduously and painfully achieved, the theme-park-and-folklore approach to cultural identity is particularly repulsive: "All a version of the Royal Wedding". It will be intriguing to note, in April, Cardiff's own reaction to a play in which the most intellectually liberated character argues that "nationalism is just a retreat from something that was greater".

In rep at the Cottesloe, RNT (0171-928 2252) to 19 April; and on tour to the New Theatre, Cardiff (01222 878889) 8-12 April