A sparky performance makes this wedding confection palatable, writes Donald Clarke

SOCIETY'S most unpleasant jobs will not do themselves. Some poor sap has to push aside blockages in the colons of pregnant cattle. Professional security staff must resist nausea while manning the barricades at Katie Melua concerts. And actors, writers and directors will - whether we like it or not - continue to work on wedding-porn comedies.

Silk hats off then to Katherine Heigl and James Marsden for making something bearable of the latest cake-and-confetti carnival. No decent person would sincerely declare 27 Dresses a good film. The sweetness of its denouement could clog arteries at 100 yards and the writers' taste for recycling Doris Day's discarded set-pieces betrays a sorry lack of ambition. But those two actors bring such fresh energy to the clichés that the film achieves a kind of cheap transcendence. That is to say: it's stupid, but it's funny (and nice).

If you've seen the poster you will know the entire plot. Heigl, the endlessly surprised star of Knocked Up and Grey's Anatomy, plays a New Yorker who, though blessed with charm, looks and good nature, seems doomed to remain the unmarried bridesmaid at other people's weddings. Mind you, she must accept a certain amount of the blame herself. For some years she has been stupidly in love with her older, more boring boss. (Edward Burns is probably not supposed to be old and boring, but he is Ed Burns.) When the sparkier Marsden turns up as a cynical wedding correspondent, she refuses to shift her affections until various statutory comic conventions have been observed. Will they fall upon one another after accidentally getting drunk? Does Bette Midler have a gay following?

Writer Aline Brosh McKenna, who adapted The Devil Wears Prada, does not add many unexpected ingredients to the stew, but Heigl has just the right sort of brow - easily furrowed - for the comedy of frustration and, aided by unfussy direction, she carries this featherweight entertainment to some unexpectedly pleasing places.

You could do much worse.