The Translucent Frogs of Quuup, New Ambassadors, London

Chris Larner, best known for his work with The Right Size comedy duo including The Play What I Wrote and Do You Come Here Often?, has conjured up the spirit of Noël Coward and Cole Porter to create this enjoyable comedy musical, a tale of "derring do and derring don't". The Translucent Frogs of Quuup was one of the more pleasant surprises of this year's Edinburgh Fringe and deserves its billing alongside the established stand-ups Richard Herring, Ed Byrne, Jason Byrne and Lee Mack for this New Ambassadors showcase.

Anthony Marigold-Bentley, a bank clerk, played by Jonathan Robbins, makes good on his promise to take his new bride Edith, Rosalie Craig, "up the Amazon" to search for the eponymous Frogs. Unfortunately for Edith, her new husband is less forthcoming in fulfilling the second part of the numerous double-entendres that pack the show. The mix of sexual tension and Boys Own silliness makes for a fun 1920s romp framed by Larner's witty narration ("shadows spread like margarine across the endless crumpet of landscape"), songs and bit parts.

Larner's charges are by no means upstaged as he leads them through "days of dense mime". Anthony and Edith have their moments in the midday sun, in particular her tuneful lament: "Love is like an aubergine/ It's a purple fruit I've read about but never seen." Rosalie Craig and Jonathan Robbins make a charming couple, affording credibility to the later, more sombre scenes of their elderly selves and following each other tightly during the rest of the play, memorably finishing one song by cooing together: "We're so thrilled we're going to have a key change!" So much do you believe the affection between the two that you can't help feel sorry for the hapless ex-bank clerk as he journeys on alone to find out the fate of the frogs while his new wife literally gets to grips with the natives and her new found sexual awakening.

Though the refrain of the opening song, "A Moment in Time" gives an underlying poignancy to the play, every comedy trick in the book is used, including a little stand-up at the beginning and a period wher the play deconstructs and the cast go out of character. I'm not convinced this exercise is absolutely necessary and would have preferred more musical numbers, but the disruption doesn't adversely affect the enjoyment of the show.

Quuup has already lengthened since Edinburgh, paying more attention to Edith's sexual experiences in Quuup and Anthony's revelations about the frogs, but there is still scope for further development of the characters and, hopefully, more musical numbers. Tightly scripted and well acted, Quuup is a delightful bit of whimsy - a simple story with a big heart.

To Friday (020-7369 1761)