Entertaining Mr Sloane, Trafalgar Studios, London

It is amazing to recall that Joe Orton had just three or four years of fame before his lover, Kenneth Halliwell, bashed his brains out in 1967, but his first success, Entertaining Mr Sloane, still delights and surprises in its subversive domestic comedy and provocative language.

Once dubbed the Oscar Wilde of Welfare State gentility, Orton's provocative sneer and suburban blasphemy are fully expressed in the iconic figure of the orphan boy Mr Sloane. Mathew Horne (of Gavin and Stacey sitcom fame) lounges around in white T-shirt and black leathers, a disruptive sexual mascot in the rivalry of a middle-aged brother and sister. An ironic soundtrack in this revival plays Jim Reeves' "Welcome to my world" and Kathy Kirby's "Secret Love" between the acts.

Sloane has been picked up in a library, of all places, by Imelda Staunton's voracious Kath (Orton and Halliwell had lately served six months in prison for defacing library books), who soon has the trousers off him while attending to a wound inflicted by a toasting fork. Kath's Dada (played by an almost ridiculously grey and senile Richard Bremmer) recognises the face of a killer in the insolently cherubic lodger, while Kath's brother Ed (Simon Paisley Day) makes his own emotional inroads by hiring him as a chauffeur.

The struggle for sexual possession, and the play's careful three-act construction, betray the influence of Pinter, and Orton hasn't yet achieved the polished, almost relentless, antithetical, aphorism-strewn style of Loot and What the Butler Saw, but the tone is clearly individual. The play's first critics found "a slice of life at its most bestial", and a sense of snakes seething round their ankles; women in housecoats weren't supposed to have sex, and old granddads weren't kicked to death behind the sofa, either.

In the last West End revival, Alison Steadman played Kath as a beehive-hairstyled auntie to her own Beverly in Abigail's Party; Staunton is even harsher, and also more desperate in her longing to have a new child with her new baby Sloane, while missing, perhaps, the scented voluptuousness of Beryl Reid in the 1969 film. But she is hilarious in her see-through nightie, and she's perfected the art of discussing her own furniture with the dry banality of a storeroom guide (her summer curtains are "more of a chintz").

Alongside this gruesome harridan of the three-piece suite and leather pouf (that's the seat, not Mr Sloane), Paisley Day's steely Ed suggests a shady career in out-of- town office blocks, and more than a hint of piously expressed racism. Feminists who loathe Orton always point to the misogyny in Kath's ability to disgust her brother and lover equally, but Orton's expression of a certain kind of homosexual psychopathology is both brilliant and frightening; Kath's an angel compared with the men.

The new young director Nick Bagnall – working with Orton enthusiast Kathy Burke as "artistic associate" – allows the pace and atmosphere to flag a little in the third act, the price of not taking a second interval. And his good work is nearly scuppered by Horne's lack of experience. Instead of glowing with satanic sexuality, Horne's Sloane mooches around as if waiting for a bag of sweets and a goodnight kiss.

The plot escalates into threats, violence and a compromise to conceal a second murder. When Kath is slapped and her dentures go flying, Ed despairs of people like Sloane ever being assimilated. "Why should a lot of vicars and actresses give cash hand-outs to hooligans who can't control themselves?" Orton, like Sloane, preferred life on the outside, and he stayed there.

To 11 April (0870 060 6632)