Jimmy Scott, Ronnie Scott's, London

"Little" Jimmy Scott, as he used to be known, is 78, a good age, to be sure, but with a frailty beyond his years and the timeless, benign gaze of the newborn and the very old and diminished. Scott's years in the wilderness when, after early success in the Fifties and Sixties, contractual disputes led to a premature retirement from the public view in Cleveland, Ohio, have not embittered this most distinctive of jazz balladeers. But we who come to see him are aware of all that we have missed, of the decades lost when Scott, whose diminutive stature and female vocal range are results of childhood illness, could not be heard trailing his phrasing over the barlines and luxuriating in every nuance of the lyrics.

So now we see him, but, to use the title of his opening number, "All of Me" is not what it was. Music-business wranglings took the part that once was his heart, and what is left is the wreck of a great beauty, whose remaining charms must be treasured and wrapped in the finest cotton wool. He didn't even appear when his backing band, the Jazz Expressions, announced his arrival, until the saxophonist went backstage to fetch him.

His quavering, ultra-slow vibrato is not the result of physical decline but a trademark style, although the shortness of his phrases and his whispered consonants pointed to that in the first couple of numbers. Gradually, he seemed to gather his strength, still singing softly in a low-key bossa version of "You Don't Know What Love Is", and then, over the last few bars, he let rip as he repeated the words of the title, in the other most famous Scott sound - that piercing, emphatic treble, cracked but powerful and intensely moving, electrifying the night.

If at other times his voice wandered, taking a seemingly sloppy stab at nailing the lyric, then here he reminded us that the lush, the lover, the loser, the soak, the fellow who has lost his job or the one "whose chick split", as Sinatra put it, has something to say, and that what he has to articulate may chill us to the core, freezing out all other senses while he pours himself a double of 90 degrees proof, pure distilled emotion. On the rocks but no water, barman.

After the Jazz Expressions, a gracefully oiled club-jazz outfit, allowed Scott a breather, he came back for "Pennies from Heaven" and a take on "The Masquerade is Over" in which he lent back and let long, sustained notes escape from his gaping wound of a mouth, followed by a sprightly, rollicking blues in 12/8. But it was those last bars of "You Don't Know What Love Is" that will long remain with me, a statement of ungarnished truth, a howl in the night, a kind of benediction.