Eerily accurate portrayal

Cabaret: JIM BAILEY AS BARBRA STREISAND; The Green Room, Cafe Royal, London

The costume is perfection. Basic black, of course, the jacket generously cut to accommodate the equally generous bosom, the lapels encrusted with rhinestones, the long skirt, slashed at the side, so legs can flash and tease. Showbiz good taste, which is to say it is too flagrantly expensive to be truly understated.

All very Barbra, all very Diva, and all eerily accurate. Which is what you'd expect from Jim Bailey, "musical illusionist". Illusionist, please, not drag queen. The art of drag is exaggeration, obsessively latching on to a gesture, a manner, just one look, and stretching it until, eventually, it loses its original shape (sometimes this can look like revenge). Bailey works small, respectful, precise, professional. Streisand's hair-fiddling, sliding walk, Bronx-stamped between-songs patter and look- at-me elegant hand movements are duplicated with detachment, not passion, which makes double sense (the original model is likewise too self-conscious to be a "hot" spontaneous performer), though the cabaret space can occasionally be unforgiving: too close, too intimate, too liable to reveal the artful, but fearsomely thick, layers of lipstick, powder and paint that make up the mask.

And too liable to pinpoint whatever flaws exist in a voice that must perforce do duty as Judy Garland (as of next week), Peggy Lee, Marilyn Monroe ... especially when the sound system is having an off night. The rule of thumb here, perhaps, is that the older the Streisand song, the more realistic the rendition. "Second Hand Rose" is a triumph that goes beyond impersonation into a rare state of being, as do "You Don't Bring Me Flowers" and "Happy Days Are Here Again", perfectly realised frauds that wittily oblige the audience to imitate a Streisand audience - "We love you, Barbra!" "You're terrific baby, the best!" "Bravo!"- though at considerably cheaper prices.

It's on tunes like "Somewhere" and "As If We Never Said Goodbye" that conviction is lacking (though not vibrato). But even this poses an interesting question, for the same might justly be said of the Streisand recordings. Is Bailey's own voice coarser and sometimes not up to the challenge of sustaining those high notes, or is this careful master of vocal portraiture merely detailing the slow slippage of a star he has actually flaunted his act in front of? It's a pretty disturbing thought: that the fake and the authentic might be heading for the same middle territory, though from completely opposite directions.