Congreve’s scintillating The Way of the World is generally described as a Restoration comedy on school syllabuses. For Phyllida Lloyd, director of the National Theatre’s new production, it’s neither a Restoration play nor exclusively a comedy.

“It was written 40 years after the Restoration, as far away as we are from, say, Look Back in Anger,” she points out. “The theatre was a very different place, overtaken by a new middle class audience, and deserted by the aristocracy - William of Orange found theatre desperately tedious.”

She suggests it was partly Congreve’s bending of a familiar form that made the play initially unpopular, but also the taste of the new bourgeoisie for sentiment and spectacle. “What resonates with the Restoration is the London setting - the beau monde, with its appetite for scandal and sex and cash, the brilliance of the language, the presence of fops, country cousins and rich widows.”

She finds the play as bleak as it is funny, one that looks forward to Ibsen and Chekhov. “There’s a sadness, a yearning that has crept in since the Restoration period. It’s remarkably Chekhovian in places - the sweeping away of an old order by a devouring younger generation. And the complexity of feeling is phenomenal, with no one character being allowed to dominate the high ground.”

She’s found it remarkable that even the most minor parts can be given some depth. “Every character is defined. It inspires you to consider the interior life of not just two or three leading characters, but of the entire cast. They are all endowed with such particular imaginations.”

She describes the structure as musical, full of great “arias” and “duets”; but also as cubist. “We get to know the characters in fragments, which often make up a jagged or contradictory whole. The trick is to be able to arrange one’s mask rapidly and often. The characters talk of escaping to another world, but the joke is that there isn’t one. Instant changes of face are essential for survival in these shark-infested waters.”

She felt it didn’t make sense to set the play in the 1990s. “I wanted to know who the characters might be in our world, but also to create a caged feeling that limits their choices and raises the stakes, for the women in particular. ”

As a result she and the actors have created their own world. “Its values are 18th century, but the audience will recognise the characters, with their appetites for property and marriage and social status, the suspicions that exist between men and women, and the horror of old age, especially for women.

So how does a character such as Millamant relate to our world? “She’s a millionaress in our terms, and many people are trying to catch her. Her apparent flippancy, her mask of indifference, is a protection against the world, and conceals her deep feeling for Mirabell. They’re both sceptical about marriage, but the demands she makes for privacy and independence are, even in contemporary terms, remarkable.”

Fiona Shaw is the latest of many leading actresses to play the part. Phyllida Lloyd feels she’s more than a match for it. “I have never watched anyone in rehearsal who can close the gap between the playwright and their own imagination with such variety: it’s as if she’s making it up as she goes along.”

The Way of the World opened yesterday at the Lyttelton Theatre (0171 928 2252). Another production opens at the Birmingham Rep on October 27.