Before the curtain even rises on a U-M Gilbert and Sullivan Society (UMGASS) show at Lydia Mendelssohn Theater, you know this isn’t your ordinary student musical. The small but very capable orchestra brings you to your feet with the opening strains of “God Save the Queen,” and everyone in the audience — Anglophile or not — sings Britain’s national anthem. (Words are printed in the program.) One year, impersonators of Queen Elizabeth and Prince Philip stepped out from behind the curtain, waved disingenuously while we all sang, and then disappeared without comment.

It’s an example of the ritual goofiness that surrounds the production of Gilbert and Sullivan comic operas, which UMGASS has been staging every year since 1947. These light operas — with spoken dialogue as well as plenty of singing — are witty social commentaries with outrageous characters who make us laugh by taking themselves too seriously.

UMGASS people take their work very seriously — while always fooling around. A mix of students, faculty, and community members (all volunteers, except for the orchestra), they have a tradition of high standards and hijinks to live up to. Sets, costumes, choreography, and physical comedy are all top notch. You actually do catch your breath when you see fourteen Tower of London beefeaters take the stage in Yeomen of the Guard, all in the traditional bright red tunics and black hats. And when the jailer jokes about keeping up with all the scheduled beheadings, the humor seems to hit close to home.

Gilbert and Sullivan are not as outdated as many people think. Precursors to the writing of Monty Python, Gilbert’s librettos have stood the test of time by using inventive rhyme and wordplay to poke fun at buffoons in positions of power. The original stories draw you in easily with their heroes and villains, star-crossed lovers, mistaken identities, and even fairies and magic potions.

Although the music is old fashioned to rock-trained ears, Sullivan knew how to write catchy tunes and toe-tapping “patter songs” (you know, “I am the very model of a modern major-general. . . .”). And because he wrote for nonvirtuoso voices, his scores have remained accessible to amateur troupes. UMGASS performers have occasional difficulty with the small-ensemble numbers, where the harmony is tight and they must pronounce the lyrics clearly in order to convey the story. But when the whole cast is onstage singing a multilayered chorus, the power and beauty of the moment puts more recent musicals to shame.

Then just as the score reaches a climax, the conductor’s tuxedo sprouts fairy wings, and you’re reminded how silly it all can be.

UMGASS performs The Pirates of Penzance Thursday through Sunday, April 3-6, at Lydia Mendelssohn.