The Funk Brothers, Royal Festival Hall, London

Before the documentary Standing in the Shadows of Motown rescued them from breadline obscurity, The Funk Brothers were forgotten musical heroes, Western pop's equivalent to the Buena Vista Social Club.

But unlike Buena Vista, The Funk Brothers had provided the soundtrack on more hit records than the Stones, The Beatles, Elvis Presley and The Beach Boys combined.

Since 1959, 13 musicians have passed through The Funk Brothers ranks, now only six of the originals are left alive and in the band. Dapper percussionist Jack Ashford tells us the last time they appeared in this country was on a 1965 Motown Revue and their most recent loss came when Johnny Griffin died on the evening of the film. "He went up to his hotel room and never came back down."

Details like that, along with the knowledge that with Eminem rather than Berry Gordy shaping the modern sound of Detroit we're unlikely to hear their kind again, make it an emotional evening, but for all the right reasons. Augmented by high-calibre veterans from the Chicago and Philadelphia scene and documentary scriptwriter Allen Slutsky on rhythm guitar, the Funks 21st-century 15-piece Revue is an astonishing living museum of soul genius.

Hobbling on with the aid of a walking-stick, the keyboard-player Joe Hunter is the oldest survivor but once seated his face comes alive, like a scientist of the groove. They run through their jukebox of dreams - the sky-kissing exuberance of "Uptight", the giddy tumult and palpitations of "Reach Out I'll Be There", the wild joy and defiant celebration of "Heatwave". The heart can't but soar.

At their work The Funks evince an effortless precision, decorated with spry filigrees of guitar from grinning elfin Joe Messina and dazzling dancing on air bass runs by Bruce Babbit - a former professional wrestler. With advertised guest star Isaac Hayes failing to show an excitable Billy Preston dressed in a bizarre yellow leather suit proves a fine replacement. Preston's infectious joy and unabashed pleasure in being boosted by this extraordinary band also shines in Stevie Winwood's two guest spots. There's a potentially cheesy audience participation slot when resident vocalist Carla Benson picks two audience members to play The Supremes to her Diana Ross on "Stop in the Name of Love".

But the depth of feeling and the triumph over venality that their music represents is absolute. On stage, Ashford's spoken-word reflections deepen the profundity of the documentary. In February they will be stepping up to receive a long overdue Lifetime Achievement Award at the Grammys, a week later Duran Duran will receive an equivalent award at the Brits. It would be hard to find a more pertinent symbol of pop music's decline.