Fifty Million Frenchmen, Royal Opera House, Linbury Studio, London

Appropriately for this musical set in Paris hotels and nightclubs, it was a nightclub hostess, the extensive Texas Guinan ("Hello, sucker!"), who first posited that fifty million Frenchmen couldn't be wrong. André Malraux, perhaps not realising that Guinan had only one subject in mind, or maybe two, pointed out sternly, "If fifty million Frenchmen say a foolish thing, it is still a foolish thing." One likes to think both, in their various ways, would have been satisfied by Ian Marshall Fisher's concert revival of the 1929 Cole Porter show.

Foolishness certainly abounds in this bit of fluff about Americans in gay Paree, gawping at monuments ("I'll buy it!") and finding that hot love has to be paid for in cold cash. The form is more revue than book show – a few years later, no one would make a musical's main love song ("You Do Something to Me") the first number. A series of comic sketches and party-piece songs are connected by some nonsense about millionaire Peter Forbes's trying to win a bet – his pal says he won't be able to live on zilch for a month, or get wealthy Looloo Carroll, who will think he's poor, to marry him. Peter chokes down his horror at the word "work" and becomes a tour guide, meeting such characters as the thrusting Violet, who wants to be shocked – a tall order from one who, shown a filthy picture, says, "Let me see that again – no, I was wrong, I don't know that man." Herbert Fields's book is, of course, dated, but hardly dead (one of its jokes turned up recently on I'm Sorry, I Haven't a Clue), and part of the fun is the quaintness of the snappy period patter: "Do you know my daughter May?" "I didn't, but thanks for the tip."

In the Twenties Cole Porter was not yet at the top of his form, and Frenchmen contains several songs that sound like early drafts of the more inventive and outrageous numbers he would later write. The jazzy but sensuous melodies, however, still exert a great deal of charm, and some of the songs have become standards for nightclub singers with a sense of humour. "The Tale of the Oyster" relates the adventures of a mollusc thrilled to be eaten by a grand society lady. My own favourite, "You've Got That Thing", contains this fervent appreciation: "You've got what Adam craved when he/ With love for Eve was tortured/ She only had an apple tree/ But you! You've got an orchard!"

Elizabeth Counsell is a superbly dry, droll Violet, both in dialogue and song. Alan Cox demonstrates an endearing blend of melancholy and stiff upper lip as poor Peter, and is incisive and touching in the show's only sad song, "You Don't Know Paree". Bryan Torfeh is an engaging smoothie-chops as the hero's cynical friend. But the rest of the cast lack the panache of some of Fisher's other Lost Musicals revivals. Their effervescence and sexual chemistry are nil, and they really should not try to dance. The biggest disappointment is Laura Michelle Kelly who, as Looloo, looks as if she's just woken up, doesn't like where she's found herself, and can perhaps be heard in some parallel universe, but not in row M.

Final performances 14 July at 3pm & 7pm (020-7304 4000)