Theatre: Strange days at the School for Scandal

School for Scandal

RST Stratford

An Experiment with an Air Pump

Hampstead, NW3

The Weir

Duke of York's, WC2

It's not all bad at the . As Sir Oliver, returning from India to discover that one of his nephews is a fraud and the other a likeable rogue, Tim Wylton is the picture of 18th-century portliness. He ought to have his portrait hanging in a National Trust house. The frizzy- haired Emma Fielding as the errant Lady Teazle is good too, while Jason O'Mara's Joseph Surface presents an immaculately poised exterior, ever ready to extricate himself with smooth lies and a fresh spin: "notwithstanding - I confess - that appearances are against me." Sheridan wrote a classic of Anglo-Irish comedy. If only the RSC, producing the play for the first time, had let us see it.

The former Cheek by Jowl team, director Declan Donnellan and designer Nick Ormerod, have taken their industrious brand of theatricality up to Stratford. They ditch the metropolitan world of 18th-century interiors in favour of busy crowd scenes against brick walls, metal staircases and balconies. This is the backstage shell of a theatre. It is the first time the cast of School For Scandal might feel at home performing on the set of West Side Story.

Onstage, the play unfolds in front of the "Prince of Wales". Members of the onstage "audience" step up, rather laboriously, enter the play. The foppish "Prince of Wales" looked as if he was enjoying this production a good deal more than I was. But then a play within a play requires a theatre critic within a theatre critic.

Deconstructionists will be quick to spot that the framing device allows us to see that the text has been created within a particular social context that may reveal far more than it intends. The particular social context, it soon becomes apparent, is fringe and touring theatre, where directorial flamboyance frequently compensates for limited resources. Characters on stage watch the action before they make their entrances, lines from one scene bleed into the next, actors hold scripts in their hands or point at members of the audience. An 18th-century comedy ends up looking like a company show from the early 1980s.

By opening the play out, the cast lose a sense of precise relationships within defined spaces: essential for powering the farcical moments. Spontaneity, quick-wittedness, the sense that actors are in control, is limited. They serve the concept. When the screen collapses and Joseph Surface is unmasked, the first-night laughter was muted.

With important boundaries blurred between private and public behaviour the comedy has to rely on heavy-handed stage business. Matthew Macfadyen's Charles bounces Sir Oliver up and down on his knee like a ventriloquist's dummy. Macfadyen swings on to the stage on a rope, hanging purposelessly in the air while the scene progresses. I enjoyed the servants running upstairs to the balcony to deliver news about there being people in the streets, at the door or down below. Crazy servants: they run up an extra flight of stairs in order to give a urgent message.

Donnellan keeps interposing himself between the actors and the play. The problem can best be seen with the asides - of which there are many. Before an actor delivers an aside there is ... (wait for it) ... a musical chord. More evidence that when you put comedy in quote marks you foul up the gags.

In An Audience Called Edouard the playwright David Pownall opened with a tableau from Manet's Dejeuner sur l'herbe and proceeded with a play about the real-life characters involved. In Sunday in the Park With George Stephen Sondheim employed Seurat's A Sunday Afternoon on the Island of La Grande Jatte. Now Shelagh Stephenson takes Joseph Wright (of Derby)'s painting An Experiment on a Bird in the Air Pump as the opening tableau for a wide-ranging play about scientific enquiry, ethics, republicanism, language and love at the very end of two centuries.

An Experiment with an Air Pump premiered in February at the Manchester Royal Exchange, and has been deservedly revived at Hampstead. Shelagh Stephenson's canvas is a good deal wider than Wright's. Like the Sondheim, and like several Stoppards, the play moves between two periods - 1799 and 1999. The set - a Newcastle house - remains the same. In 1799 the scientist's wife thinks she's ignored by her husband. In 1999, the scientist's husband, an English lecturer, has been made redundant, while the wife, a research scientist, ponders earning big money working for business. In one neat twist, the plumber, (Martin Ledwith) is as credulous about spontaneous combustion and extra terrestrials as any figure from 1799.

Among the cast, Barbara Flynn is excellent as the wife suffocating within a marriage: her husband appears to do to her, unconsciously, what in the painting he does, consciously, to the bird. And Tom Smith's portrayal of Roget, a young physician who likes lists, has an impressive naturalness. Always intriguing, the debates in An Experiment spread themselves a bit thin. Stephenson's interest in the subjects outstrips her interest in the characters. As the dramatic chiaroscuro of Wright's painting shows: good pictures are about what you leave out as much as what you put in.

If you haven't seen it yet, hurry to The Weir. I liked Conor McPherson's play when it opened in a studio space. Seeing it on the main stage of the Duke of York I liked it a lot more. Watching this seemingly low-key anecdotal play, set in a small bar in the west of Ireland, in a small dingy Royal Court Upstairs, you become part of that world. See it on a West End stage and its modesty becomes daringly cheeky. The dogged humour takes on a life of its own: defying expectation.

McPherson has great ease as a storyteller. He takes time, builds mood, lets stories unfold. He's wonderfully served by the performances. There isn't a better piece of ensemble acting in London. It's not just the way they talk, it's the way they listen. The move to a bigger stage allows Jim Norton's hilarious portrayal of the feisty, unpredictable Jack to go up several notches. This contrasts beautifully with Brendan Coyle's slow-moving thoughtfulness as the publican. He fills the stage with a watchful strength.

Director Ian Rickson establishes a brooding, unhurried world with consummate skill. It's essential for creating the camp fire atmosphere round which the stories are going to be told. McPherson stirs up plenty of attack, bad blood, spookiness, humour and sorrow. Rickson handles these shifts in pace and tone with the kind of artistry that doesn't show. Each round of drinks, and there are a great many, changes the mood like a new hand of cards. And we know every character will hold an ace.

'The School For Scandal': RST Stratford (01789 295623), to 24 October; Barbican, EC2 (0171 638 8891) to 21 November. 'An Experiment With An Air Pump': Hampstead, NW3 (0171 722 9301), to 7 November. 'The Weir': Duke of York's, WC2 (0171 565 5000), to 23 January.