The Betty Carter system of man-management is simple but effective. Firstly, you choose employees (in Betty's case, the musicians for her trio) who are above all young and malleable. Secondly, you intimidate them to within an inch of their lives. Thirdly, you offer the occasional sexual come-on - delivered in the full public glare of on-stage performance - to act as both a carrot and a stick. As a method of team-building, it might not work for accountancy, but it sure as hell does the trick in jazz. Faced with the terrifying presence of their employer, Carter's trios - which seem to be getting younger as she gets older - begin to develop almost paranormal powers of inter-group communication. True, they may not look very happy, but they sound magnificent. Not, of course, that they have much say in how they sound at all.

As the three young men took the stage for their warm-up number, they were the image of chipper, well- adjusted young executives, dressed up for the office in sober dark lounge suits. When they began to play, they smiled at each other glowingly as they passed the tune between them like a basketball. Then - in a whoop of applause and an ample shimmer of her black velvet brocade dress - on came Betty, and within a few seconds of "Close Your Eyes", she was already on the bassist's case, standing right in front of him and shaking her head with displeasure. He looked confused, then contrite, and then, as she moved on to the pianist, mightily relieved. It wasn't that there was anything wrong with what he was playing, but rather that she just wanted him to know she was there.

The art of the female jazz vocalist is an elusive one and there are many practitioners who don't seem to have an art at all, just the stylistic accoutrements of the role, such as snapping fingers, soulful glances and a repertoire of dodgy show-tunes. Carter, needless to say, has the art above all else; above, almost, the need for a voice at all. Because she doesn't sing like an angel, like Ella Fitzgerald, or like a saxophone, like Billie Holiday - whose grainy, pitted sound allows us to read vulnerability, loss of innocence, anything you like really, into her delivery - Carter's instrument is not diminished by age at all, although she is now 67. And also unlike the other great singers, Carter's gift is something that can't be considered separately from the music it is part of. The sound is an elongated swoon, the accent the cute timbre of a child pretending to be posh, and while the words of the songs are as clear as daylight, you can soon forget that you're listening to words at all. When she leaves them behind to scat, it's a seamless progression into a private language that seems perfectly natural, and not the usual be-bop-a-roonie beloved of lounge singers everywhere, Even the choice of songs seems almost irrelevant. Carter once made "The Surrey With the Fringe onTop" into perhaps the most swinging jazz vocal ever recorded.

In a long, deliciously intense performance at Ronnie Scott's on Thursday, Carter was every bit as good as you expected. Though sparks flew and the band were occasionally singed by her burning looks, the scoldings were relatively few. Indeed, as she came to stand an inch away from the drummer towards the end of the set, watching intently as he played a brief solo, the look on her face was one of the purest love. The pride of ownership was there too, but it must be the love that keeps them warm.

If King Lear played the double bass, he would look rather like Peter Ind. Ind - who for years owned the Bass Clef club that is now the Blue Note, home to Goldie and drum and bass - came on stage for a couple of numbers during the guitarist Martin Taylor's solo show at the Pizza Express Jazz Club round the corner from Ronnie's in Soho. Though they hadn't played together for 20 years, they immediately melded into one, bass and treble singing along in a dream of quiet, unforced jazz (not exactly the Betty Carter method). As befits one of the leading guitarists in the world, Taylor was impeccably good. But what in the past has sometimes seemed like a perfection of technique earned at the expense of a truly personal sound - all clean lines with no rough edges - had become just about perfect on all fronts. At the end, Taylor played a show-stopping version of "I Got Rhythm" which simultaneously interwove bassline, rhythm figure and lead filigree in a way which defied the eyes, the ears, and probably the laws of gravity. The audience of guitarists both real and manque loved it, in a way that only guitar enthusiasts can, for their devotion is legendary. They'll buy not just the CDs, but the videos, the tutor-books, the plectrums and, if you could market them, plaster casts of their favourite axe-hero's fingers. Give them half a chance in fact, and they'd buy the fingers themselves.