With an irresistible new play starring two robots, Britain's Alan Ayckbourn proves again that he has no equal in the English-speaking theater.

"Henceforward," which opened in London recently, is a science-fiction-slanted hilarity which shows all of Ayckbourn's typical daring and imaginative stagecraft.It also demonstrates what some Britons long have contended - that playwright Ayckbourn is a genius, a writer far more "important" than his painfully funny comedies would make it appear.

He is not yet 50, yet "Henceforward" is his 34th play. No. 35 already has opened outside London.

He is also a prolific and award-winning director of his own and other writers' plays. He runs his own theater in the North Sea resort town of Scarborough. But posterity will remember him as a writer and may rate him higher than most people have thought.

It used to be held that Ayckbourn's plays concentrated too narrowly on his favorite subject, the foibles and failures of England's middle class. His humor was considered too British to convulse audiences around the world.

Yet as the "Henceforward" program says, his plays "have been translated into 24 languages and are performed on stage and television on virtually every continent of the globe."

He has just allowed the first movie to be made of one of his plays. He is so highly considered in Japan that Tokyo's Nihon University is staging an exhibition of his work next April which will become a permanent display.

It was once equally fashionable to dismiss Ayckbourn's plays as mere fluff, funny but empty, notable mainly for the technical impossibilities he writes into every script.

Yet consider what Sir Peter Hall, for 15 years head of Britain's National Theater, recently told critic Sheridan Morley:

"If in 50 years time you want to know about the ethos of Thatcher's Britain, then look at . . . the way his characters are getting more and more motivated by greed and self-interest. He is now the playwright of an uncaring society.

"If you look back at his plays you can already see the 1970s and '80s very clearly mapped out. His plays are nothing less than the document of our age."

"Henceforward" projects aspects of our age into "sometime quite soon." It is a frightening picture.

A composer of electronic music is barricaded among high-tech gadgetry in an apartment under siege from vicious cross-sexual gangs. Visitors, festooned with attack alarms, brave the area only in armor-plated limousines.

Padding jerkily around the apartment is a malfunctioning android, a female robot baby-sitter. Its design was scrapped when "teething problems" led one early model to pop a child into a microwave.

The play's plot revolves around the composer's scheme to gain visiting rights to his 13-year-old daughter. He modifies his robot to help him present a scene of domestic bliss - and then the complications start.

Before they end, Ayckbourn has debated whether humans are better than machines, depicted a society enslaved by its own technology, shown the plight of an artist who cares more for his creations than for people and portrayed the nightmare our society easily could become.

And this is a comedy?

It certainly is. "The exhilarating Ayckbournian paradox," said critic Michael Billington, "is that the darker it gets the funnier it becomes."

In fact, one facet of Ayckbourn's genius is to make even tragedy funny. He once wrote an entire act about a desperate woman trying to commit suicide, and it was hilarious. His "Woman in Mind" showed a woman having a nervous breakdown, and it was side-splitting.

But he is not merely funny. He chronicles our age by ruthless truthfulness about people and the uncanny way his characters reflect flaws and strains in society as a whole.

His newest play, for instance, "Man of the Moment," focuses on a robbing thug turned by the media into a rich and popular star. It had its premier at Ayckbourn's small north coast theater, where all his plays are first shown.

Most playwrights would consider it a good life's work to write even six plays as funny, penentrating and successful as those by Alan Ayckbourn. But next year, as every year, Ayckbourn will write another one.

And as always, he will write his 36th play virtually at one sitting, in about three days. "Genius" is the only word.