HE IS LIKEABLE, charming, and very funny. In theory, Alan Davies should be able to knock out a couple of hours (including interval) of comedy. In practice, things aren't so easy. This is largely because stand- ups are ill-suited to performing in theatres over such a length of time. No plot, no drama, no other characters: just one man and his mike banging on until it's time to go home. Inevitably, comedians struggle. When was the last time you sat, transfixed, as someone talked about himself, without interruption, for an hour and a half?

Nor are matters helped by the nature of Davies's performance. He is genial, not angry; observatory, not self-revelatory. And the absence of anger and pain makes even less dramatic an event that was not exactly long on drama in the first place. Geniality can only get you so far.

On the plus side, Alan Davies is that rarity: a comedian who makes you laugh. He achieves this not through jokes but by studding his monologues with perfect phrases. "'Oi, mate' - the phrase that every shopkeeper dreads." "If you want to avoid getting a job: when you have an interview - wear flip-flops." "Ten-thousand-metres heats: fuck off, they're not athletes, they're refugees." "Shocking garments - waistcoats." Every line is delivered off-the-cuff, with minimum effort, to maximise the effect.

The monologues, too, are way above average. There is an inspired rant against the countryside - "I'm campaigning for paving it over" - which concludes with Davies wondering what it is about fresh air that makes you turn in so early that you have to tape Match of the Day. There is a fine confrontation between a haggling hippy back from India and a newsagent who is reminded of the old times as they row over the price of the Guardian. And another as Alan, a self-confessed "Travelcard meanie" who will never take a taxi if his four-zone card is still effective, has a bit of bother down in the tube station at midnight.

For all this, if you are given the chance to see Davies live you should take it. Although such chances are rare; for a chunk of primetime Saturday- night TV and a well-judged performance in a financial-services ad ensured that Davies had sold out before he had even begun.

Finally, the quibble. Two-thirds of the way through, Davies degenerates from assured comedian to playground titterer as he lets his comic genius run wild on the subject of ... Pooh. But he meant faeces, not Winnie. "Why don't we talk about poo?" he enquired with a Paxmanesque intensity. Because, Alan, the last time we talked about poo was when we were six, and even then, it struck us as being a somewhat childish topic for discussion. After analysing poo, he zoned in on cats. Fine, the audience loved it (as, shame to say, they had the poo chat), but cats bore me rigid. After cats, and following a minor diversion on mopeds, he moved on to pants. It wasn't totally unfunny - it's just the combined effect of the subjects under discussion left one despairing why Davies doesn't attempt something more challenging. Poo, cats and pants aren't exactly cutting-edge: they're the stuff of Billy Bunter's Remove rather than Life.

Fortunately, he recovered to ask, "How many hips does the Queen Mother have?" And he rounded off with a well-observed piece on the fat issue in relationships - "It wasn't a fat question, it was a fabric enquiry." This was well up to the usual standard and reminded one that when he puts away childish things he is a very funny man.

Duchess Theatre, WC2 (0171 494 5076), to Sat.