Midway through his seventh decade, Tom Jones is no longer the ravisher of nubility that made him one of showbiz's favourite caricatures. To his credit, he knows it.

Unlike other singers of his vintage, for whom age is the signal to break out the leather trousers, he's growing not just older but up. Although part of him - to judge by some vestigial pelvic thrusts - would still love to be as dirrty as Christina Aguilera, he has managed a compromise. There's just enough cautious thrusting tonight to justify the £50 ticket price, but the focus of this Teenage Cancer Trust benefit is his voice.

Essentially, Jones just stands around and sings in that volcanic voice. The audience watch passively till near the end, when someone's pent-up adoration is expressed in the form of a flying white thong. There's always one, isn't there? He used to mop his forehead with undies, then hand them back to their owners, but he's no longer that kind of boy. Here he makes only a cursory inspection before thundering into another song.

Very nice, but there is an insurmountable problem: a Tom Jones without the sexy sauce is a Tom Jones without a point. Yes, the man can sing like a buffalo; yes, his live renditions of black-hearted stormers such as She's a Lady and Delilah still rouse a tingle (even if, disgracefully, he treats the latter as a jolly singalong). But it's hard not to notice how laboured he sounds, as if the voice has to negotiate leathery impediments on its way out. Semi-concealed by the sheer heft of his baritone, meanwhile, is a lack of expressiveness that gnaws away at both familiar tunes (What's New Pussycat, greeted with wall-to-wall delight) and unfamiliar ones (a few nibbles from 2002's hip-hop escapade, Mr Jones).

Guest Jools Holland's elegant piano highlighted Jones's lumbering way with a pop classic. Still, what's the alternative? Mick Jagger pretending to be 20? On balance, and even without his priapic appeal, Jones is the better bet.