Lyric Theatre presents Dorothy July 23, 8 p.m. and July 24, 2:30 p.m. at le Petit Trianon Theatre, 72 N. Fifth St., San Jose.

The show is part of the company's 2-year-old Discovery Series, which focuses on reviving "lost" operettas dating from 1860 to 1920.

How Dorothy might have gotten lost is an intriguing case, given its initial popularity and close ties to the legendary songwriting team of William Gilbert and Arthur Sullivan.

"If you read almost any of the biographies of Gilbert and Sullivan, you would invariably come across mention of Dorothy. On its own merits, Dorothy was the most popular show in England in the 19th century, in fact," says Marc Kenig, director of Dorothy.

Dorothy was written by composer Alfred Cellier and librettist Benjamin Charles Stephenson. The show was a romantic farce set in the 1740s in the English countryside, where two wealthy young ladies don disguises and test the love of their beaus. With 931 shows, the original production of Dorothy ran about 200 performances longer than its famous contemporary, Gilbert and Sullivan's The Mikado.

Dorothy may have outsold The Mikado, but it was a friendly competition. Cellier was a music director for Gilbert and Sullivan, and Stephenson had also worked with Sullivan. The ex-business manager of Gilbert and Sullivan's theater, the Savoy, produced Dorothy.

Naturally, some similarities existed between Gilbert and Sullivan's operettas and Dorothy, but the show was different enough to give the top songwriting team pause. "Gilbert and Sullivan did a fair amount of soul-searching wondering why Dorothy was more popular than their brand of operetta," Kenig says. "They thought about building a different theater or creating different sort of show."

Of course, it turns out that Gilbert and Sullivan needn't have worried at all. That might be partly due to an unusual advantage that Gilbert and Sullivan enjoyed.

"Stage shows, especially from this era and the Edwardian period, would change over time," Kenig says. "Producers would do the 'new and improved' thing or a new artist would come in and a new song would be written for them. With Gilbert and Sullivan, because they were self-produced, that didn't happen. They established a signature score and a performing tradition that was relatively unchanging. For shows like Dorothy, every time they were revived, it might be changed. Also the actors would ad lib new things or add new topical references."

That's a major reason why Dorothy has been a challenge to revive. No one version can be found in its entirety. Kenig and music director Neil Midkiff pieced together a new performing edition of Dorothy using a score found online and a libretto (a musical's script) provided by Lyric Theatre's previous music director, Don Tull.

The score and the libretto didn't always match up, but sometimes the discrepancies were helpful. For example, in a place where the score indicated a dance-only number, with no singing, the same section in the libretto had lyrics for the number, hinting that originally the song might have been danced and sung.

Midkiff was also able to make some corrections to typos in the score. Typographical errors on scores were common in the days of low-tech printing when errors were too costly or time-consuming to fix. "Over time, these scores would collect errors," Kenig says.

Kenig and Midkiff have worked since the beginning of the year to reconstruct Dorothy. In addition to their detective work on the score and libretto, they have made a few minor updates to the language and humor, for a 21st century audience's understanding.

The show has also been simplified a little to suit Lyric Theatre's semi-staged concert production. This format will not feature sets and costumes. Actors will be accompanied by a piano and hold scores as they perform. Although Dorothy is sung in English, Lyric Theatre will provide supertitles to help audiences catch lyrics to songs they won't be familiar with.

Ultimately, just why nobody knows these once-popular songs anymore--why Dorothy has almost disappeared--is hard to say. But with new shows opening all the time, and the changing tastes of audiences, even many of the best works eventually get edged out.

"The future history of most stage works, regardless of when they are written, is to get lost," Kenig says. "Gilbert and Sullivan, Shakespeare, they're really the exception to the rule. Even Gilbert and Sullivan came to be viewed as dated until they were professionally revived 15 years after they stopped writing. Many shows don't have that excellent fate and they just get fondly remembered and people put the scores on their bookshelves and they collect dust, because there are new shows--every year, there are more new stage shows. That's how these shows become lost. It has nothing to do with their merits or the beauty of the music, as we're finding with the entirety of the Discovery Series."

Tickets are $15. Call 408.986.1455 or see www.lyrictheatre.org.