The proper children's or family play - as opposed to an adaptation of a classic book - is becoming a rarity in theatres, which seem to prefer to reduce the box-office risk with the lure of a well-known title. The exceptions are Alan Ayckbourn's annual Scarborough treat and the adventurous little Southwark Playhouse, whose original Christmas play is becoming a bit of a tradition. This year's offering is written by David Cregan. It takes place partly in the Elysian fields, where one of the unicorns is proving difficult because it longs to be useful as well as beautiful, and partly in Peckham, where lowly bank clerk George Jackson is proving just as difficult to his long-suffering family.
George isn't beautiful and he doesn't want to be useful. He just wants £2m so that he can enjoy a life of holidays in Spain, swimming pools, meaty barbecues and lots of sherry. What's more, every morning the family breakfast is ruined by his confident expectation that the £2m will arrive in the post, followed by the bitter disappointment of dashed hopes.
So when George's son hears about an email address called unicorn.help@Elysian-fields.com, he sends a message asking for his father to be happy. A big mistake, as George doesn't want to be happy, just rich. Soon a temperamental unicorn is trampling the petunias in Peckham under the watchful eye of his keeper Stanley, who quickly decides that south-east London is heaven on the grounds that "once you've seen Tesco, the Elysian fields lose their attraction".
Cregan's play doesn't quite hold together either as fable or drama, but you forgive its failings because it is charm itself - as is the unicorn, a flirtatiously frolicsome panto horse with a golden horn. It is directed with terrific simplicity by Jane Howell and acted with twinkle-eyed commitment by an able cast led by Brian Protheroe. A slight delight.
· Until January 4. Box office: 020-7620 3494.
