After a hard day in the tiny studio at Hitsville USA, the musicians who created Motown's 1960s chart-toppers headed for the jazz lounges hidden in Detroit's black suburbs. There, freed from the tight structures of three-minute pop songs, they would spend the night playing the kind of music on which they had cut their teeth. So the chance to see the surviving members of that great aggregation returning to their natural habitat, rather than to the concert halls in which they performed during the world tour that followed a successful documentary film three years ago, seemed enticing.

Sadly, too few of them survive to make the latest incarnation of the Funk Brothers work in any setting whatsoever. Several of the key musicians died after the film, Standing in the Shadows of Motown, had been completed. Others who participated in the rapturously received British concerts of 2004 no longer travel with the group. Which leaves just two: Jack Ashford, whose touches of vibraphone and tambourine distinguished many of the hits, and the veteran keyboardist Joe Hunter, Motown's first staff musician.

They are not enough. Virtually submerged in a band made up of anonymous hacks, with a battery of singers of extremely uneven quality, they are now participating in something that bears more resemblance to third-rate cruise-ship entertainment than to a joyous and dignified revival of a golden past.

The absentees - men such as Earl Van Dyke, James Jamerson, Bennie Benjamin, Robert White, Richard "Pistol" Allen, Joe Messina, Eddie Willis, Uriel Jones and Johnny Griffith - may have been mere session musicians, but their individual talent and character shaped a body of music that has long outlasted its expected lifespan. If these soulless travesties of Uptight, You Can't Hurry Love, Ain't Too Proud to Beg and My Guy have any value, it is to demonstrate that the magic is not transferrable.

· Ends tonight (box office: 020-7439 0747), then touring.