ONCE UPON A MATTRESS was a vehicle for Carol Burnett, who used the leading role of Princess Winifred the Woebegone as a stepping stone to television immortality. The show is based on the fairy tale of the princess whose royal lineage is proven when a pea lying beneath 20 mattresses disturbs her sleep. The show's one-dimensional fairy tale plot exaggerates the frothy, cute tendencies inherent in most American musical comedies. With minimal character development and a score which also lacks distinction, the play depends on a showcase of individual talents rather than the merits of a coherent story.

Fortunately for director Ralph Gibson and the audience, the Leverett House production features a cast of talented musical-comedy actors and actresses who manage to keep the aimless plot amusing. Although Burnett's humor set the pace in the original production, Harriet Mermes's appealingly Klutzy and earthy Winifred does not carry the show. Mermes's best moment occurs in the second act, when she has the stage to herself as she attempts to fall asleep. She yawns and stretches and mugs her way to bed only to be foiled by the pea under her mattresses.

George Hunt is particularly entertaining as Prince Dauntless the Drab, the weak-willed mother's boy in search of a wife and a way to untie the apron strings. Hunt doesn't sting all that well, but his comic sense is more than adequate, and he manages to stop the show a few times with broad gestures and a bewildered, hapless expression.

His mother, who contrives the bogus legitimacy test to foil Winifred as she has foiled all previous applicants for her son's hand, is rather simply played by Judy Banks. The character requires bitchiness and vanity, two qualities which Banks humorously displays in her first scene. However, Banks fails to develop her character any further, so the only potentially evil elements in the play ends up harmless and benign.

The shallow plot of Mattress breeds shallow characterizations. A gaggle of supporting actors is thus given freedom to attempt to steal the show, and two in particular come very close to succeeding. Peter Grand turns in a sparkling performance as the Wizard, a show-biz type turned minister. In the first act, he offers a frighteningly accurate imitation of Bob Ewbank, host of the Newlywed Game. And he walks off with the second act by virtue of an impressive display of magic tricks.

Tom Shea is also good as King Sextimus, the mute sex-fiend, hamming up his mime as much as possible. His gestures tend to get repetitive, but again the plot, which has him chasing courtiers around the stage every few minutes, is more at fault than the actor. Shea peaks in a number where he attempts to explain the facts of life to his son, the erstwhile bridegroom.

One of the pitifully few sub-plots involved two lovers, played by Macaire Henderson and Scott Atherton. Henderson brings a fine voice and strong stage presence to the show, while Atherton only manages to look ill-at-ease.

BUT DESPITE the strong leads, it is the chorus that finally saves Mattress from becoming an endless series of one-liners and talent-show acts. The chorus provides transitions, which are otherwise neglected in the text, and it fleshes out numerous empty scenes.

The male chorus in the Leverett production is particularly good, but several members of the female chorus repeatedly broke character, looking as if they were thinking of what to do after the show or how many papers they had to write by Christmas.

Technically, the production is severely cramped by the confines of Leverett's Old Library, which is about as suitable for theater as Burr A. The lack of space is particularly evident in the tacky plywood castle walls, which serve as the only set. The choreography, on the other hand, makes the most of the tiny stage: the dance sequences are adequate, although the full-cast numbers look like barely organized mayhem with practically no one having any room to move.

To director Gibson's credit, the slick production legs only in the unnecessarily long second act. Gibson can perhaps be criticized for failing to produce conspicuous interaction between members of the cast, most of whom seem to be aware of other actors only when they must speak to them. Again, this is partially a flaw in the play itself, which shows off individuals and not the company as a whole.

Overall, the cast does overcome the weaknesses of the book to present a funny, entertaining production. Musical comedy aficionados and those who seek pleasant diversion will enjoy the show. Of course, those who hate musicals are advised not to see it. You'll probably feel better if you stay at home this weekend and finish the reading for your tutorial, but you'll be missing a fine show.