Exiles, NT Cottesloe, London<br/>A Right Royal Farce, King's Head, London<br/>The Comedy of Errors, Globe, London

I wish I had seen Harold Pinter's staging of Exiles in 1970. Hailed as a major discovery of an overlooked gem, it must have done James Joyce's only surviving play script a lot more favours than the National's new, deadly revival. James Macdonald's below-par production - lamentably, his NT debut - feels more like a dirge, performed by a bunch of stiffs, than a marital drama about adulterous temptations and treacherous friends.

Completed in 1915 - when Joyce had started to draft Ulysses, and the publication of A Portrait of The Artist as a Young Man was imminent - Exiles does have a degree of autobiographical interest. It mirrors, in a refracted form, the author's own highly unconventional relationship with Nora Barnacle and his obsession with Amalia Popper, a convalescent student whom he tutored in Trieste. An intellectual author called Richard (Peter McDonald) has returned from self-imposed exile in Europe to suburban Dublin. Advocating radically liberated marital relations, he insists that his common-law wife, Bertha, is free to embark on an affair with his old pal, Robert, while clearly writhing inside with jealousy. He is also trying to salve his own conscience because he is unfaithful and hooked on Robert's cousin, Beatrice.

In literary terms, what's most fascinating is how Joyce's exchanges, now and then, have a starkness which makes them sound like a precursor of Sam Beckett's more tightly honed style. In its scenario, Exiles is also intriguingly akin to Pinter's great Seventies play Betrayal, as well as chiming with the sadomasochistic interrogations in the playwright's earlier short, The Lover. Exiles was clearly morally avant-garde in its challenging arguments about open relationships, influenced by and pushing beyond Ibsen. However, this is a creaky play in other respects and Joyce certainly doesn't have a consistently sharp ear for dialogue here. His exchanges can sound peculiarly like a wooden translation and McDonald is often flailing badly, leaving his cast looking, psychologically, out of focus.

He does discover sporadic gripping moments over the course of three hours, involving repressed desires and twisted power games. Dervla Kirwan, as Bertha, rises to fiery anger while Marcella Plunkett's Beatrice is palpably tense under her demure front. But the drawling gents are ridiculously rigid, enfuriatingly slow-paced and low on energy.

Adrian Dunbar's Robert is a smarmy cad without any credibly seductive, impulsive passion. McDonald's Richard just seems an unpleasant bore, endlessly staring off into the middle-distance with a little frown. He is perhaps looking for someone to shed some more light on his character and the funereally gloomy set.

After this, you're dying for a glimmer of humour. Well, A Right Royal Farce is the second, supposedly controversial satire to spring, half-formed, from the combined wits of Toby Young and Lloyd Evans. This duo were previously responsible for the galumphing sex farce, Who's the Daddy, which caricatured David Blunkett and the top dogs at The Spectator. At least that involved the slight frisson of Young and Evans being the magazine's own drama critics. But, heavens to Betsy, their new Buckingham Palace fantasy is just howlingly unfunny and incompetent, with no trenchant topicality at all.

The Queen is dead and Harry's rotten (and garbled) plot to grab the crown involves dosing an already lecherous Prince Philip with Viagra and dressing up a dumb blonde as Diana's ghost to get William sectioned. Puerile garbage. You wouldn't have put this on at school, and director Alan Cohen's slapstick fights are gobsmackingly inept.

What a joy, after this, to find Shakespeare's four-twins farce, The Comedy of Errors, directed with élan. The Globe's stage, for a change, looks as pretty as a picture with its thumping great faux-marble columns wittily repeated in miniature (by designer Janet Bird) to create playful receding perspectives, where the cast chase each other into dwarf villas and round a maze of alleys. The costumes are Ancient World-going-on-Empire line with some florescent Sixties touches (and obviously a nod to A Funny Thing Happened on the Way to the Forum).

Luscombe's ensemble are a cornucopia of comic business, from the centurion who keeps bursting into tears to Sarah Woodward's splendidly huffy Adriana - the wife confounded by identical husbands. After the lovely hand-in-hand egalitarianism of the Dromio twins' final exit, the curtain call seems a tad odd, sidelining the duo of serving men and giving centre-stage to their paired masters and ladies. But, all in all, this is charming fun, with composer Julian Philips's score also playing a starring role. As well as punctuating the slapstick punch-ups with perfectly timed whistles and gongs, Philips beautifully changes the mood, with a simple flute to accompany speeches of startling, transcendent tenderness.

k.bassett@independent.co.uk

'Exiles' (020 7452 3000) to October 26; 'A Right Royal Farce' (020 7226 1916) to 27 August; 'The Comedy Of Errors' (020 7401 9919) to 7 October