Laurence and Gus made a Fringe name for themselves with the long-form sketch, extended routines in which they explored every comic angle of their set-up and personality trait of their complex characters. But they didn't half go on a bit.

This time around they've got for a more quickfire approaches, with dozens of shorter episodes. The gimmick, though, is that one flows on from the last, like a comedy relay race. So the director from the 'bad audition' sketch that opens the show is seen in the second playing poker with a recently-divorced friend, who in turns goes on to discuss his relationship difficulties with his dry cleaner in sketch three, and so the baton is passed on and on.

It's rather a stagey contrivance, more like a dramatic writing exercise than the basis for a real show, but it does ensure the proceedings flow fluidly, with no (or at lest very few) awkward transitions.

The duo are seasoned enough to realise the limitations of the form, however, and things start to get interesting when they start subverting their own rules, with Gus Brown, for instance, reappearing as a character Lawrence Howarth earlier played. Eventually the whole concept comes brilliantly unravelled although they ill-advisedly then try to pick it back up again. After such a thorough trashing of the conceit, it's hard to go back to believing the pretence of the formal sketch.

Much of the comedy is of the sort you admire, rather than laugh heartily at ­ a sort of stage equivalent of Steve Coogan's Saxondale. The writing is mature, with three-dimensional characters uttering authentic lines, from which wry comedy emerges naturally. The crux is normally people who aren't quite what they seem, such as the sergeant-major racked by insecurity or the thrusting, boastful executive who's actually been made redundant.

Other creations are weirder ­ the mental projection of a dead teenager, or Knorman Knopfler, Mark's offspring struggling to find his own niche ­ yet still seem reasonably convincing because the duo are such fine performers. Guy is generally the more mature, authoritative type, while the jowlier, jauntier Laurence more prone to playing up, but they are both talented actors, so it's not as simple as the traditional double-act mechanic.

Nothing, in fact, is simple here ­ which is perhaps why it's not the source of many belly laughs. But there's still plenty to enjoy in the rich writing if you're prepared to accept it on those terms.

Steve Bennett