Theatre: Masha, Tasha, Irina, Charles

Three Sisters

Birmingham Rep

Britannicus

Albery, WC2

Ugly Rumours

Tricycle, NW6

It didn't look as if this was going to work. The auditorium of the Birmingham Rep is on a steep slant. Hayden Griffin, the designer, presents the drawing room and dining room of the Prozorov household on two rafts, without walls, and with a cloudy skyscape behind. Susan Wooldridge's Olga begins by telling her sister, in a muted sing- song tone, that it was 11 years ago that they left Moscow. From Row K, we might have been on the deck of a ship, watching people on the quayside.

In this open space, it's tricky to control changes in mood. So Bill Bryden's production doesn't offer the vertiginous shifts in atmosphere achieved in Max Stafford- Clark's recent Out of Joint production. At a full three hours, the brusque insensitivities, as one point of view bumps up cruelly against another, become less pronounced. But, this exerts its force thanks to the sharply individualised performances: as distinct as the black, grey and white dresses worn by the sisters. Without leaving the town, Bryden's cast go on eventful journeys.

Of course this is and One Sister-in-Law. Eve Matheson's Natasha is suitably ghastly, talking incessantly about her children. To be fair, it's not as if any of her three sisters-in-law help her out with the childcare. Felicity Dean's brooding Masha spends most of the evening in a horizontal position, erupting with a desperate clinginess in the final act. Rachel Pickup is a glamorous, spirited Irina: it's some provincial post office that has her behind the counter.

Charles Dance is best known as a TV and film actor. His courteous and imposing Vershinin looks caught uneasily between his instinct for naturalness and the need to hit the volume. The glowering presence of Jasper Britton's Solyony cleverly suggests the turmoil of a man who can't help his rudeness. All the performances grow. When the play moves outdoors, and the two-dimensional birch trees fly in, the cast take command of the airy stage. I hope this production transfers to London. It might find a better home.

Harold Wilson wasn't reading his Racine when he said that a week was a long time in politics. When you're observing the classical unities, a day's an awful long time. At the end of Britannicus, the second Racine tragedy triumphantly presented by the Almeida in the West End, Nero's tutor Burrus, played with aquiline cragginess by David Bradley, says: "I have already lived a day too long."

We have just heard of the death of Nero's half-brother (a passionate Kevin McKidd). Junia, his love (a fraught and fragile Joanna Roth), whom Nero wants to marry, has taken refuge in the temple. The Roman mob has killed Britannicus's tutor (the devilish courtier John Glover). With Nero half-crazed, and his mother awaiting her death, it hasn't been what journalists would call a slow news day.

Robert David MacDonald's forceful and nimble version retains the alexandrine hexameters. Jonathan Kent's thrilling production, more successful than his first, keeps the deceptions, passions and power politics absolutely in focus. Maria Bjornson's grand apartment design combines the world of Louis XIV with that of the present day. When Barbara Jefford's Albina enters, she switches on the lights. To one side, there are two fishtanks. Behind these, later on, Toby Stephens's Nero can be seen eavesdropping in a sickly glow.

As Nero's mother Agrippina, Diana Rigg gives her best performance since Mother Courage. In a sparkling two-piece and pearls, she twitches cigarettes in her fingers with impatience or snaps open her handbag to fish out a hankie. She's wonderfully pointed, articulate and modern. Putting on her warmest maternal tones, she schmoozes her demonic son: Mother Cunning.

Stephens mixes cold sarcasm with a childish awkwardness. His fingers paw at his palm; his knees stick together when he sits down. His greased- down hair gives him a tyrant's puppy fat. He finds moments of exquisite tension: when he pauses, a chill runs through the audience as if he might have forgotten his lines. There's only a hint of the lip-curling, double- breasted villain that Rik Mayall gives us with Alan B'Stard.

Thanks to Rory Bremner, John Bird, John Fortune, Harry Enfield and Private Eye's St Albion parish newsletter, we know what the jokes about New Labour are: Tony is preachy; Gordon is bitter; the two of them hate each other; everyone sucks up to Murdoch; spin-doctors control every speech; they are all conservatives; and nothing has changed.

What can theatre add? At the Tricycle, Tariq Ali and Howard Brenton's satire Ugly Rumours takes its title from Blair's rock band at Oxford. It's half-way between a student revue and a Christmas panto. We meet Tony- boy, Cherry-pop, Gordon Macduff and two spin-doctors, Polly Mendacity and Charlie Farrago. Rupert Murdoch has a koala bear; Richard Branson is Biggles; and the ghost of John Smith rattles the chains of compromise. An insight into the authors' minds: the wicked spin-doctors are sexy and elegant women who work out at the gym.

A natural boulevard comedian, Neil Mullarkey plays Blair with a tentative alertness - nice and ineffectual - that suggests he ought to have been playing John Major. He's well contrasted with Gordon Kennedy's rumpled bassett hound of a Gordon Macduff. Sylvia Syms doubles up wittily as Mrs Thatcher, a crazy cobwebby figure living in the cellar of Number 10, and Mrs Windsor, a keen gardener with green wellies and a hand outstretched for a whisky.

The authors' main thrust is that focus groups are replacing democracy. If most satire has an energy that makes its targets larger than life, this slack, brittle affair does the opposite. Ali and Brenton clearly knew what they thought about this lot before they started. It's teacherly and condescending. They luxuriate in their dislike of New Labour. Consequently they never land a decent punch. A strong sense of hurt and resentment comes off the stage: not between Gordon and Tony, but between those in power and those - older people in Old Labour - who aren't. So, bad news then for William Hague.

The only people who might enjoy this show are Blair and Brown themselves. If this is the worst that can be thrown at them, they could be the first to have a good laugh.

'': Birmingham Rep (0121 236 4455), to 21 November. 'Britannicus': Albery, WC2 (0171 369 1740), in rep to 12 December. 'Ugly Rumours': Tricycle, NW6 (0171 328 1000), to 28 November.