Christopher Guest owns the mockumentary genre, with his “Waiting for Guffman,” “Best in Show” and “A Mighty Wind” being among some of the finest comedies of the past decade. Most of his imitators have failed to capture that semi-improvised quirkiness, but “Confetti,” a new bit of British drollery, is one of the better offerings. Our cousins across the pond have a knack for understated comedy, which is what you need for a mockumentary. You want people behaving as if what they’re doing is perfectly normal, not jumping around like clowns.

“Confetti” centers on a topic ripe with possibilities: weddings. A bridal magazine is sponsoring a contest for “most original wedding,” with the winner getting a house. Three finalists have been selected by the editors, their weddings to be held the same day and judged by a panel of experts. (Are there “experts” in the field of creative wedding-holding?)

Couple one, Matt (Martin Freeman) and Sam (Jessica Stevenson), want a wedding in the style of the old Hollywood musicals, complete with singing and dancing. That Sam is tone deaf is not viewed as a problem. Couple two, Josef (Stephen Mangan) and Isabelle (Meredith MacNeill), are professional tennis players who want tennis-themed nuptials, if their highly competitive natures don’t destroy them first. And couple three, Michael (Robert Webb) and Joanna (Olivia Colman), are nudists who want a good old-fashioned naked wedding.

Debbie Isitt, who conceived and directed the film, makes it clear early on where things are going. Josef and Isabelle are too argumentative to be anything more than buffoons, and the nudists are obviously in the movie only to be laughed at. It’s Matt and Sam, the musical couple, who earn our support and sympathy as sweet kids who just want to have a lovely wedding. Martin Freeman already has points in his favor from playing Tim in the British version of “The Office,” but the less-known Jessica Stevenson is just as instantly likable.

All three couples work well as comedy teams, too, and Isitt lets them play off each other enough to show the comedic chemistry going on. (Extra kudos to Robert Webb and Olivia Colman for managing to be funny and unselfconscious even when they’re completely naked.) And there’s a fourth couple: Jason Watkins and Vincent Franklin as the preciously gay wedding planners hired to help the three pairs plan their ceremonies. Their increasing stress levels and their cute, loving relationship with each other actually provide some of the film’s most warmhearted moments.

It is, ultimately, more a “warm” film than a hysterically funny one. It has its moments, certainly, but it doesn’t fully capitalize on the possibilities of its premise. One sees elements reminiscent of the Guest films — the competition of “Best in Show,” the fractured couples trying to relate as in “A Mighty Wind,” and the earnestly tacky performances (wait’ll you see these weddings!) of “Waiting for Guffman.” “Confetti” was inspired by the best, in other words, and though it feels like it should be funnier, it is a smiley and amusing affair full of happy endings and goodwill.

B (1 hr., 40 min.; R, abundant non-sexual nudity, scattered harsh profanity.)