FOR someone who has made some of the most beautiful music of the last 50 years - in fact, probably of the last 50,000 years or however long it is since the first musicians found another use for two sticks besides producing hot orangey stuff - Brian Wilson makes an unduly modest entrance.

At Portsmouth Guildhall on Monday, where the man who wrote all those feelgood surfing anthems despite never having set foot on a surfboard, performed the legendary "lost" Beach Boys album Smile in its entirety, it was a good 30 seconds before I realised he was on stage at all.

Rock gods aren't renowned for their self-effacing natures and usually prefer to stride rather than simply walk on to a stage. I don't imagine Freddie Mercury, for instance, could have even walked into a room without leaving a gap for the applause.

When Brian Wilson walked onto the stage, it was still shrouded in darkness. When the lights came up, we saw a tight huddle of about ten singers and musicians, mostly young and gorgeous and all harmonising beautifully.

Perched on a stool at the back of this group was a pale, middle-aged man, mothily dressed and looking faintly ill at ease. Not, as you could be forgiven for thinking, an insurance salesman doing a spot of impromptu canvassing, but one of the handful of living music stars we can justifiably describe as geniuses. Brian Wilson, in other words.

Such understated behaviour could easily be attributed to the mental and physical ravages Wilson has undergone in the last 40 years. A man like Wilson, who has not so much peered into the abyss as thrown himself into it on the end of a very old, frayed bungee rope, probably doesn't have the energy or inclination to live up to our expectations of traditional rock star behaviour.

Judging from his minimal stage antics during Monday's concert (a few literal hand mimes and the occasional smile, but very little else), I'm not sure Wilson is even capable of playing the strutting, preening rock god - a part which demands a great deal of whooping, arm-waving and rather disturbing facial contortions (at least if you're following the pattern set down by Mick Jagger).

But even if he were, I think Wilson would choose to let the music speak for itself. His talent and reputation are more than enough to carry a show and, crucially, his complete avoidance of "Jagger-isms" has the added bonus of ensuring he leaves the stage with his dignity intact.

The Butlins Redcoat approach to live performance of some pop and rock stars can smack of desperation - as if they suspect that the audience might get bored and look at something else if they stop moving for a moment.

No wonder Mick can't seem to stand still.