Anyone for Demis Roussos?

The defining moment in Abigail's Party comes when man-eating horror Beverly is given a bottle of wine. "Oh lovely!" she says. "Cos Laurence likes a drop of wine, actually. Oh it's Beaujolais. Fantastic! Won't be a sec, I'll just pop it in the fridge."

It's hard to believe, but it is 20 years since bored, bitchy Beverly's social pretensions were so cruelly exposed. An extraordinary 16 million viewers tuned in to BBC2 on 1 November 1977 to watch Abigail's Party, and stayed with it, riveted by a drama that put Mike Leigh and his improvisational style on the map. The play was not Leigh's first, nor even his first for television. But it was the first to bring him to the widespread notice of an unsuspecting public and the first full-length television drama to be constructed partly without a script.

Abigail's Party, originally performed as a stage play at the Hampstead Theatre in 1973, follows events during an evening in a suburban living room as Beverly - a hostess-from-hell creation that established Alison Steadman as an actress of formidable gifts - and her uptight, pretentious husband Laurence entertain three of their neighbours. They are nerdy nurse Ange, her inarticulate husband Tone, and angst-ridden Sue - her nerves brought on by the fact that she's had to come next door while her teenage daughter Abigail, a character we never see, throws her first party. Beverly's incessant nasal whine, her continual putdowns of her husband, and attempts to seduce the hunky Tone turn the evening into a social nightmare. She reserves the heights of crassness for the climax of the drama when Laurence has a heart attack in the middle of Beethoven's Fifth - nagging at him as she bends over his prostrate body while blowing cigarette smoke straight into his face.

Everyone who remembers Abigail's Party has their own, cringe-making, favourite moment: the stiff handshake Laurence proffers after dancing with Ange and Sue; or perhaps the priceless argument over who wants to listen to Demis Roussos. For Terry Hands, the former artistic director of the Royal Shakespeare Company, it's when Bev advises Ange on lipstick application: "That speech about how it should all be internal - that attitude mirrors things like aromatherapy, positive thinking," Hands says. "It prefigures all that New Age stuff."

Theatr Clwyd, of which Hands is now director, is about to stage a revival of the play. Why does he think it was so important? "It showed the genius of Mike Leigh in putting his finger satirically on the shortcomings and social problems of our time. I've always thought of Mike as a latter day Ben Jonson. It was the first description of the generation that voted in Mrs Thatcher: the Seventies wannabes, their acquisi- tiveness, aspirations, and so on. It's a play about Essex Man. It's a comedy, but a very black comedy."

For those involved it was hard work. By now Leigh had honed his very personal method of creating character, notably in Bleak Moments and Nuts in May, two earlier television dramas that were critically admired but, unlike Abigail's Party, did not register so deeply with the audience. In researching her part as Ange, Janine Duvitski was sent to a supermarket in character, to pick out only items which her alter ego would have bought. Then she remembered that she needed food for her own dog. Leigh, who had been creeping down the aisles behind her, suddenly reared up to remind her: "Your character doesn't have a dog!"

Despite the impressive viewing figures, Abigail's Party sparked a great deal of criticism. In the Sunday Times, Dennis Potter lead the assault on Leigh's often cruel portrayal of resentment, self-delusion, and social climbing. He condemned the play as "a prolonged jeer, twitching with genuine hatred, about the dreadful suburban tastes of the dreadful lower-middle classes". (For a time, the issue of putting red wine in the fridge was even debated in the letters pages of the Times).

The audience does seem to be invited to sneer at the tastelessness of the world inhabited by Beverly and Laurence - the terrible clothes and decor, conversational banalities, and contorted speech mannerisms. Leigh, however, doesn't think there is any reason for misgiving. Charges that he deals only in caricature are, he has said, "uniquely English. I won't even say British, because I don't get it from Ireland or Scotland. Of course my people are types. But they're not stereotypes. They're too idiosyncratic and individual for that."

Leigh's casts, knowing how much detail goes into character preparation, are surely entitled to believe there is much more to him."Mike's area is the glory of everyday nothingness which he elevates to great drama," says Timothy Spall, who worked with Leigh on Life is Sweet and Secrets and Lies. "The minutiae of people's lives becomes of the utmost importance. And the people of his films are never seen anywhere else, except when they are destroyed in the tabloid newspapers or in patronising documentaries."

Twenty years on, four of the five cast are still working (Harriet Reynolds, who played Sue, died in 1992). The award-winning Steadman, Leigh's ex- wife, is by far the best known, recently as Mrs Bennett in Pride and Prejudice. Her friend Duvitski, who is currently sharing the Old Vic stage with Steadman in The Provok'd Wife, has been in One Foot in the Grave and Waiting For God. John Salthouse (Tone) played Det Insp Galloway in The Bill and Mike Monroe in Eastenders, and Tim Stern (Laurence) appears in the BBC's forthcoming classic serial, Tom Jones.

But is Abigail's Party still relevant? Fiona Buffini is directing the Theatr Clwyd production as an updated version in which the action is transposed to Cardiff and references have been made more relevant to the 1990s. "We had to change surprisingly little," she says. "It's still a wonderful play. In Abigail's Party you see beyond the surface in a character such as Laurence. You see his pain and you can't help but feel compassion for him." Hands agrees. "What I would say is that the lack of communication between people - that is still here. The people in Abigail's Party have just become the new mobile phone owners. The warnings are still valid." !