A very unusual theatrical production opened at the Wilbur, Monday night. Called "Let's Make an Opera," it is a fantastic melee of play, opera, and community sing which you won't believe until you see. At one point during the evening the traditionally stony Boston audience shouts for a full minute "To-whoo," "Kaaah," "Prrrooo," and "Pink! Pink! Pink!"

The show starts simply enough as a bedtime story about a nineteenth century chimney-sweep. Then the children and storytellers decide to make an opera out of the tale. As the opera is written, the author gives the audience a part, singing four songs: a prologue, epilogue and two entre-acts. The first set of "Let's Make an Opera" is devoted to the problems of amateurs writing an opera, rehearsing the opera with all sorts of trouble from noisy children, and finally rehearsing the audience. The second act is the opera itself.

The author, Benjamin Britten, a leading composer of modern operas, must have had a wonderful time writing this. The complete originality of the first act either charms or annoys the listener, depending on his own responsiveness. The children appear as awful amateurs who have only enthusiasm. And when conductor Norman Del Mar comes out to rehearse the audience, the thing really gets silly. His charm and cunning slowly leads the audience into loud and violent song. At one point, they must imitate birds, and the "Kaaahs" and "To-whoos" ring out through the theatre.

During the second act, the uniqueness fades. Mr. Del Mar changes from his informal, rehearsal garb of the first act to conductor's full dress, and the opera begins. It is here that Benjamin Britten's music comes out as the intriguing element. Between the scenes of the first act, music written for four hands on a plane and percussion gave hints of what follows. Britten unfolds music of gay brightness, reminiscent of his work in the humorous opera "Albert Horring." The plot of the bedtime story is naturally flabby, and the acting of the children, though excellent, is not enough to sustain interest.

The strangeness of audience participation annoyed the traditionalists who refused to sing and sat glumly through the play. A girl sitting next to me, a non-singer, left after the first act. But I liked the play; I sung.